diff --git a/internal/services/appservice/helpers/app_stack.go b/internal/services/appservice/helpers/app_stack.go
index 5836bc2220c1..47798eed5f90 100644
--- a/internal/services/appservice/helpers/app_stack.go
+++ b/internal/services/appservice/helpers/app_stack.go
@@ -128,6 +128,7 @@ func windowsApplicationStackSchema() *pluginsdk.Schema {
 					"~14",
 					"~16",
 					"~18",
+					"~20",
 				}, false),
 				AtLeastOneOf: windowsApplicationStackConstraint,
 			},
@@ -282,6 +283,7 @@ func windowsApplicationStackSchema() *pluginsdk.Schema {
 			"~14",
 			"~16",
 			"~18",
+			"~20",
 		}, false)
 		r.Schema["java_version"].AtLeastOneOf = windowsApplicationStackConstraintThreePointX
 
diff --git a/internal/services/appservice/helpers/function_app_schema.go b/internal/services/appservice/helpers/function_app_schema.go
index 5ebae00fcad8..5850a023d300 100644
--- a/internal/services/appservice/helpers/function_app_schema.go
+++ b/internal/services/appservice/helpers/function_app_schema.go
@@ -1006,7 +1006,7 @@ type ApplicationStackLinuxFunctionApp struct {
 	// Note - Function Apps differ to Web Apps here. They do not use the named properties in the SiteConfig block and exclusively use the app_settings map
 	DotNetVersion         string                   `tfschema:"dotnet_version"`              // Supported values `3.1`, `6.0`, `7.0` and `8.0`.
 	DotNetIsolated        bool                     `tfschema:"use_dotnet_isolated_runtime"` // Supported values `true` for `dotnet-isolated`, `false` otherwise
-	NodeVersion           string                   `tfschema:"node_version"`                // Supported values `12LTS`, `14LTS`, `16LTS`, `18LTS`
+	NodeVersion           string                   `tfschema:"node_version"`                // Supported values `12LTS`, `14LTS`, `16LTS`, `18LTS, `20LTS``
 	PythonVersion         string                   `tfschema:"python_version"`              // Supported values `3.12`, `3.11`, `3.10`, `3.9`, `3.8`, `3.7`
 	PowerShellCoreVersion string                   `tfschema:"powershell_core_version"`     // Supported values are `7.0`, `7.2`
 	JavaVersion           string                   `tfschema:"java_version"`                // Supported values `8`, `11`, `17`
@@ -1017,7 +1017,7 @@ type ApplicationStackLinuxFunctionApp struct {
 type ApplicationStackWindowsFunctionApp struct {
 	DotNetVersion         string `tfschema:"dotnet_version"`              // Supported values `v3.0`, `v4.0`, `v6.0`, `v7.0` and `v8.0`
 	DotNetIsolated        bool   `tfschema:"use_dotnet_isolated_runtime"` // Supported values `true` for `dotnet-isolated`, `false` otherwise
-	NodeVersion           string `tfschema:"node_version"`                // Supported values `12LTS`, `14LTS`, `16LTS`, `18LTS`
+	NodeVersion           string `tfschema:"node_version"`                // Supported values `12LTS`, `14LTS`, `16LTS`, `18LTS, `20LTS`
 	JavaVersion           string `tfschema:"java_version"`                // Supported values `8`, `11`, `17`
 	PowerShellCoreVersion string `tfschema:"powershell_core_version"`     // Supported values are `7.0`, `7.2`
 	CustomHandler         bool   `tfschema:"use_custom_runtime"`          // Supported values `true`
@@ -1105,6 +1105,7 @@ func linuxFunctionAppStackSchema() *pluginsdk.Schema {
 						"14",
 						"16",
 						"18", // preview LTS Support
+						"20",
 					}, false),
 					ExactlyOneOf: []string{
 						"site_config.0.application_stack.0.dotnet_version",
@@ -1357,6 +1358,7 @@ func windowsFunctionAppStackSchema() *pluginsdk.Schema {
 						"~14",
 						"~16",
 						"~18",
+						"~20",
 					}, false),
 					ExactlyOneOf: []string{
 						"site_config.0.application_stack.0.dotnet_version",
diff --git a/internal/services/appservice/linux_function_app_resource_test.go b/internal/services/appservice/linux_function_app_resource_test.go
index cccf63c7cc6d..09e3f51d7dfe 100644
--- a/internal/services/appservice/linux_function_app_resource_test.go
+++ b/internal/services/appservice/linux_function_app_resource_test.go
@@ -1147,6 +1147,15 @@ func TestAccLinuxFunctionApp_appStackNodeUpdate(t *testing.T) {
 			),
 		},
 		data.ImportStep("site_credential.0.password"),
+		{
+			Config: r.appStackNode(data, SkuBasicPlan, "20"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+				check.That(data.ResourceName).Key("kind").HasValue("functionapp,linux"),
+				check.That(data.ResourceName).Key("site_config.0.linux_fx_version").HasValue("NODE|20"),
+			),
+		},
+		data.ImportStep(),
 		{
 			Config: r.appStackNode(data, SkuBasicPlan, "14"),
 			Check: acceptance.ComposeTestCheckFunc(
diff --git a/internal/services/appservice/linux_function_app_slot_resource_test.go b/internal/services/appservice/linux_function_app_slot_resource_test.go
index 7bed04f799cf..24ad06b47ad8 100644
--- a/internal/services/appservice/linux_function_app_slot_resource_test.go
+++ b/internal/services/appservice/linux_function_app_slot_resource_test.go
@@ -868,6 +868,15 @@ func TestAccLinuxFunctionAppSlot_appStackNodeUpdate(t *testing.T) {
 			),
 		},
 		data.ImportStep("site_credential.0.password"),
+		{
+			Config: r.appStackNode(data, SkuStandardPlan, "20"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+				check.That(data.ResourceName).Key("kind").HasValue("functionapp,linux"),
+				check.That(data.ResourceName).Key("site_config.0.linux_fx_version").HasValue("NODE|20"),
+			),
+		},
+		data.ImportStep("site_credential.0.password"),
 		{
 			Config: r.appStackNodeUpdateTags(data, SkuStandardPlan, "18"),
 			Check: acceptance.ComposeTestCheckFunc(
diff --git a/internal/services/appservice/linux_web_app_resource_test.go b/internal/services/appservice/linux_web_app_resource_test.go
index c8cac59a96ac..a89199725687 100644
--- a/internal/services/appservice/linux_web_app_resource_test.go
+++ b/internal/services/appservice/linux_web_app_resource_test.go
@@ -930,7 +930,7 @@ func TestAccLinuxWebApp_withNode18LTS(t *testing.T) {
 
 	data.ResourceTest(t, r, []acceptance.TestStep{
 		{
-			Config: r.node(data, "20-lts"),
+			Config: r.node(data, "18-lts"),
 			Check: acceptance.ComposeTestCheckFunc(
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
@@ -939,6 +939,21 @@ func TestAccLinuxWebApp_withNode18LTS(t *testing.T) {
 	})
 }
 
+func TestAccLinuxWebApp_withNode20LTS(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_linux_web_app", "test")
+	r := LinuxWebAppResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.node(data, "20-lts"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep(),
+	})
+}
+
 func TestAccLinuxWebApp_withJre8Java(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_linux_web_app", "test")
 	r := LinuxWebAppResource{}
diff --git a/internal/services/appservice/linux_web_app_slot_resource_test.go b/internal/services/appservice/linux_web_app_slot_resource_test.go
index c0e6334d23a6..e5b90051ff37 100644
--- a/internal/services/appservice/linux_web_app_slot_resource_test.go
+++ b/internal/services/appservice/linux_web_app_slot_resource_test.go
@@ -965,6 +965,36 @@ func TestAccLinuxWebAppSlot_withNode16LTS(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_linux_web_app_slot", "test")
 	r := LinuxWebAppSlotResource{}
 
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.node(data, "16-lts"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("site_credential.0.password"),
+	})
+}
+
+func TestAccLinuxWebAppSlot_withNode18LTS(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_linux_web_app_slot", "test")
+	r := LinuxWebAppSlotResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.node(data, "18-lts"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("site_credential.0.password"),
+	})
+}
+
+func TestAccLinuxWebAppSlot_withNode20LTS(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_linux_web_app_slot", "test")
+	r := LinuxWebAppSlotResource{}
+
 	data.ResourceTest(t, r, []acceptance.TestStep{
 		{
 			Config: r.node(data, "20-lts"),
diff --git a/internal/services/appservice/windows_function_app_resource_test.go b/internal/services/appservice/windows_function_app_resource_test.go
index a514084a295b..688d4138b1ce 100644
--- a/internal/services/appservice/windows_function_app_resource_test.go
+++ b/internal/services/appservice/windows_function_app_resource_test.go
@@ -1087,6 +1087,22 @@ func TestAccWindowsFunctionApp_appStackNode18(t *testing.T) {
 	})
 }
 
+func TestAccWindowsFunctionApp_appStackNode20(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_windows_function_app", "test")
+	r := WindowsFunctionAppResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.appStackNode(data, SkuConsumptionPlan, "~20"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+				check.That(data.ResourceName).Key("kind").HasValue("functionapp"),
+			),
+		},
+		data.ImportStep(),
+	})
+}
+
 func TestAccWindowsFunctionApp_appStackNodeUpdate(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_windows_function_app", "test")
 	r := WindowsFunctionAppResource{}
@@ -1116,6 +1132,22 @@ func TestAccWindowsFunctionApp_appStackNodeUpdate(t *testing.T) {
 			),
 		},
 		data.ImportStep("site_credential.0.password"),
+		{
+			Config: r.appStackNode(data, SkuBasicPlan, "~18"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+				check.That(data.ResourceName).Key("kind").HasValue("functionapp"),
+			),
+		},
+		data.ImportStep("site_credential.0.password"),
+		{
+			Config: r.appStackNode(data, SkuBasicPlan, "~20"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+				check.That(data.ResourceName).Key("kind").HasValue("functionapp"),
+			),
+		},
+		data.ImportStep("site_credential.0.password"),
 	})
 }
 
@@ -2810,6 +2842,7 @@ resource "azurerm_windows_function_app" "test" {
 `, r.template(data, planSku), data.RandomInteger, version)
 }
 
+// nolint: unparam
 func (r WindowsFunctionAppResource) appStackNode(data acceptance.TestData, planSku string, nodeVersion string) string {
 	return fmt.Sprintf(`
 provider "azurerm" {
diff --git a/internal/services/appservice/windows_function_app_slot_resource_test.go b/internal/services/appservice/windows_function_app_slot_resource_test.go
index 765d1e81491d..2e48b4d61d18 100644
--- a/internal/services/appservice/windows_function_app_slot_resource_test.go
+++ b/internal/services/appservice/windows_function_app_slot_resource_test.go
@@ -757,6 +757,22 @@ func TestAccWindowsFunctionAppSlot_appStackNode(t *testing.T) {
 	})
 }
 
+func TestAccWindowsFunctionAppSlot_appStackNode20(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_windows_function_app_slot", "test")
+	r := WindowsFunctionAppSlotResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.appStackNode(data, SkuStandardPlan, "~20"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+				check.That(data.ResourceName).Key("kind").HasValue("functionapp"),
+			),
+		},
+		data.ImportStep("site_credential.0.password"),
+	})
+}
+
 func TestAccWindowsFunctionAppSlot_appStackNodeUpdate(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_windows_function_app_slot", "test")
 	r := WindowsFunctionAppSlotResource{}
@@ -778,6 +794,14 @@ func TestAccWindowsFunctionAppSlot_appStackNodeUpdate(t *testing.T) {
 			),
 		},
 		data.ImportStep("site_credential.0.password"),
+		{
+			Config: r.appStackNode(data, SkuStandardPlan, "~20"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+				check.That(data.ResourceName).Key("kind").HasValue("functionapp"),
+			),
+		},
+		data.ImportStep(),
 	})
 }
 
@@ -2221,6 +2245,7 @@ resource "azurerm_windows_function_app_slot" "test" {
 `, r.template(data, planSku), data.RandomInteger, version)
 }
 
+// nolint: unparam
 func (r WindowsFunctionAppSlotResource) appStackNode(data acceptance.TestData, planSku string, nodeVersion string) string {
 	return fmt.Sprintf(`
 provider "azurerm" {
diff --git a/internal/services/appservice/windows_web_app_resource_test.go b/internal/services/appservice/windows_web_app_resource_test.go
index fbdf60cf1ee3..2fbe83a33b2a 100644
--- a/internal/services/appservice/windows_web_app_resource_test.go
+++ b/internal/services/appservice/windows_web_app_resource_test.go
@@ -1076,6 +1076,21 @@ func TestAccWindowsWebApp_withNode18(t *testing.T) {
 	})
 }
 
+func TestAccWindowsWebApp_withNode20(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_windows_web_app", "test")
+	r := WindowsWebAppResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.node(data, "~20"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("site_credential.0.password"),
+	})
+}
+
 func TestAccWindowsWebApp_withMultiStack(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_windows_web_app", "test")
 	r := WindowsWebAppResource{}
diff --git a/internal/services/appservice/windows_web_app_slot_resource_test.go b/internal/services/appservice/windows_web_app_slot_resource_test.go
index 09b66ec3f410..57f46a7970a3 100644
--- a/internal/services/appservice/windows_web_app_slot_resource_test.go
+++ b/internal/services/appservice/windows_web_app_slot_resource_test.go
@@ -788,6 +788,21 @@ func TestAccWindowsWebAppSlot_withNode18(t *testing.T) {
 	})
 }
 
+func TestAccWindowsWebAppSlot_withNode20(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_windows_web_app_slot", "test")
+	r := WindowsWebAppSlotResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.node(data, "~20"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("site_credential.0.password"),
+	})
+}
+
 func TestAccWindowsWebAppSlot_withNodeUpdate(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_windows_web_app_slot", "test")
 	r := WindowsWebAppSlotResource{}
@@ -807,6 +822,13 @@ func TestAccWindowsWebAppSlot_withNodeUpdate(t *testing.T) {
 			),
 		},
 		data.ImportStep("site_credential.0.password"),
+		{
+			Config: r.node(data, "~20"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("site_credential.0.password"),
 	})
 }
 
diff --git a/website/docs/r/linux_function_app.html.markdown b/website/docs/r/linux_function_app.html.markdown
index ce666dc233ba..3817f80fc3dc 100644
--- a/website/docs/r/linux_function_app.html.markdown
+++ b/website/docs/r/linux_function_app.html.markdown
@@ -173,7 +173,7 @@ A `application_stack` block supports the following:
 
 * `java_version` - (Optional) The Version of Java to use. Supported versions include `8`, `11` & `17`.
 
-* `node_version` - (Optional) The version of Node to run. Possible values include `12`, `14`, `16` and `18`.
+* `node_version` - (Optional) The version of Node to run. Possible values include `12`, `14`, `16`, `18` and `20`.
 
 * `python_version` - (Optional) The version of Python to run. Possible values are `3.12`, `3.11`, `3.10`, `3.9`, `3.8` and `3.7`.
 
diff --git a/website/docs/r/linux_function_app_slot.html.markdown b/website/docs/r/linux_function_app_slot.html.markdown
index 83ca48869fa3..262182db6cef 100644
--- a/website/docs/r/linux_function_app_slot.html.markdown
+++ b/website/docs/r/linux_function_app_slot.html.markdown
@@ -636,7 +636,7 @@ An `application_stack` block supports the following:
 
 * `java_version` - (Optional) The version of Java to use. Possible values are `8`, `11` & `17` (In-Preview).
 
-* `node_version` - (Optional) The version of Node to use. Possible values include `12`, `14`, `16` and `18`
+* `node_version` - (Optional) The version of Node to use. Possible values include `12`, `14`, `16`, `18` and `20`
 
 * `powershell_core_version` - (Optional) The version of PowerShell Core to use. Possibles values are `7` , and `7.2`.
 
diff --git a/website/docs/r/windows_function_app.html.markdown b/website/docs/r/windows_function_app.html.markdown
index eaa644b4d07a..089d27dabd91 100644
--- a/website/docs/r/windows_function_app.html.markdown
+++ b/website/docs/r/windows_function_app.html.markdown
@@ -171,7 +171,7 @@ A `application_stack` block supports the following:
 
 * `java_version` - (Optional) The Version of Java to use. Supported versions include `1.8`, `11` & `17` (In-Preview).
 
-* `node_version` - (Optional) The version of Node to run. Possible values include `~12`, `~14`, `~16` and `~18`.
+* `node_version` - (Optional) The version of Node to run. Possible values include `~12`, `~14`, `~16`, `~18` and `~20`.
 
 * `powershell_core_version` - (Optional) The version of PowerShell Core to run. Possible values are `7`, and `7.2`.
 
diff --git a/website/docs/r/windows_function_app_slot.html.markdown b/website/docs/r/windows_function_app_slot.html.markdown
index cc89081362af..210494bd7ba5 100644
--- a/website/docs/r/windows_function_app_slot.html.markdown
+++ b/website/docs/r/windows_function_app_slot.html.markdown
@@ -629,7 +629,7 @@ An `application_stack` block supports the following:
 
 * `java_version` - (Optional) The version of Java to use. Possible values are `1.8`, `11` and `17` (In-Preview).
 
-* `node_version` - (Optional) The version of Node to use. Possible values are `~12`, `~14`, `~16` and `~18`.
+* `node_version` - (Optional) The version of Node to use. Possible values are `~12`, `~14`, `~16`, `~18` and `~20`.
 
 * `powershell_core_version` - (Optional) The PowerShell Core version to use. Possible values are `7`, and `7.2`.
 
diff --git a/website/docs/r/windows_web_app.html.markdown b/website/docs/r/windows_web_app.html.markdown
index a0946cf755da..6db5e6f3bfbc 100644
--- a/website/docs/r/windows_web_app.html.markdown
+++ b/website/docs/r/windows_web_app.html.markdown
@@ -189,7 +189,7 @@ ASP.NET V4.8 | v4.0
 
 ~> **NOTE:** For currently supported versions, please see the official documentation. Some example values include: `1.8`, `1.8.0_322`,  `11`, `11.0.14`, `17` and `17.0.2`
 
-* `node_version` - (Optional) The version of node to use when `current_stack` is set to `node`. Possible values are `~12`, `~14`, `~16`, and `~18`.
+* `node_version` - (Optional) The version of node to use when `current_stack` is set to `node`. Possible values are `~12`, `~14`, `~16`, `~18` and `~20`.
 
 ~> **NOTE:** This property conflicts with `java_version`.
 
diff --git a/website/docs/r/windows_web_app_slot.html.markdown b/website/docs/r/windows_web_app_slot.html.markdown
index 8291761e04fa..9ff437ea43e0 100644
--- a/website/docs/r/windows_web_app_slot.html.markdown
+++ b/website/docs/r/windows_web_app_slot.html.markdown
@@ -184,7 +184,7 @@ An `application_stack` block supports the following:
 
 ~> **NOTE:** For compatible combinations of `java_version`, `java_container` and `java_container_version` users can use `az webapp list-runtimes` from command line.
 
-* `node_version` - (Optional) The version of node to use when `current_stack` is set to `node`. Possible values include `~12`, `~14`, `~16`, and `~18`.
+* `node_version` - (Optional) The version of node to use when `current_stack` is set to `node`. Possible values include `~12`, `~14`, `~16`, `~18` and `~20`.
 
 ~> **NOTE:** This property conflicts with `java_version`.