diff --git a/postgres/changelog.d/18047.added b/postgres/changelog.d/18047.added
new file mode 100644
index 0000000000000..b55f8acdb82c5
--- /dev/null
+++ b/postgres/changelog.d/18047.added
@@ -0,0 +1 @@
+Added warning when ssl option for Postgres check is invalid
diff --git a/postgres/datadog_checks/postgres/config.py b/postgres/datadog_checks/postgres/config.py
index 7437033f7206a..276f5a7b68555 100644
--- a/postgres/datadog_checks/postgres/config.py
+++ b/postgres/datadog_checks/postgres/config.py
@@ -31,7 +31,7 @@ class PostgresConfig:
     GAUGE = AgentCheck.gauge
     MONOTONIC = AgentCheck.monotonic_count
 
-    def __init__(self, instance, init_config):
+    def __init__(self, instance, init_config, check):
         self.host = instance.get('host', '')
         if not self.host:
             raise ConfigurationError('Specify a Postgres host to connect to.')
@@ -75,6 +75,9 @@ def __init__(self, instance, init_config):
         ssl = instance.get('ssl', "allow")
         if ssl in SSL_MODES:
             self.ssl_mode = ssl
+        else:
+            check.warning(f"Invalid ssl option '{ssl}', should be one of {SSL_MODES}. Defaulting to 'allow'.")
+            self.ssl_mode = "allow"
 
         self.ssl_cert = instance.get('ssl_cert', None)
         self.ssl_root_cert = instance.get('ssl_root_cert', None)
diff --git a/postgres/datadog_checks/postgres/postgres.py b/postgres/datadog_checks/postgres/postgres.py
index 081385f11793e..7a8d83316c30e 100644
--- a/postgres/datadog_checks/postgres/postgres.py
+++ b/postgres/datadog_checks/postgres/postgres.py
@@ -112,7 +112,7 @@ def __init__(self, name, init_config, instances):
                 "DEPRECATION NOTICE: The managed_identity option is deprecated and will be removed in a future version."
                 " Please use the new azure.managed_authentication option instead."
             )
-        self._config = PostgresConfig(self.instance, self.init_config)
+        self._config = PostgresConfig(self.instance, self.init_config, self)
         self.cloud_metadata = self._config.cloud_metadata
         self.tags = self._config.tags
         # Keep a copy of the tags without the internal resource tags so they can be used for paths that don't
diff --git a/postgres/tests/conftest.py b/postgres/tests/conftest.py
index 390d95cdbc54a..91ad37bdde6ab 100644
--- a/postgres/tests/conftest.py
+++ b/postgres/tests/conftest.py
@@ -106,13 +106,13 @@ def pg_replica_logical():
 
 @pytest.fixture
 def metrics_cache(pg_instance):
-    config = PostgresConfig(instance=pg_instance, init_config={})
+    config = PostgresConfig(instance=pg_instance, init_config={}, check={'warning': print})
     return PostgresMetricsCache(config)
 
 
 @pytest.fixture
 def metrics_cache_replica(pg_replica_instance):
-    config = PostgresConfig(instance=pg_replica_instance, init_config={})
+    config = PostgresConfig(instance=pg_replica_instance, init_config={}, check={'warning': print})
     return PostgresMetricsCache(config)
 
 
diff --git a/postgres/tests/test_metrics_cache.py b/postgres/tests/test_metrics_cache.py
index efb1067263ecf..4507e2c6d06a8 100644
--- a/postgres/tests/test_metrics_cache.py
+++ b/postgres/tests/test_metrics_cache.py
@@ -28,7 +28,7 @@
     ],
 )
 def test_aurora_replication_metrics(pg_instance, version, is_aurora, expected_metrics):
-    config = PostgresConfig(instance=pg_instance, init_config={})
+    config = PostgresConfig(instance=pg_instance, init_config={}, check={'warning': print})
     cache = PostgresMetricsCache(config)
     replication_metrics = cache.get_replication_metrics(version, is_aurora)
     assert replication_metrics == expected_metrics
@@ -50,7 +50,7 @@ def test_dbm_enabled_conn_metric(pg_instance, version, is_dbm_enabled, expected_
     pg_instance['dbm'] = is_dbm_enabled
     pg_instance['collect_resources'] = {'enabled': False}
     pg_instance['collect_database_size_metrics'] = False
-    config = PostgresConfig(instance=pg_instance, init_config={})
+    config = PostgresConfig(instance=pg_instance, init_config={}, check={'warning': print})
     cache = PostgresMetricsCache(config)
     instance_metrics = cache.get_instance_metrics(version)
     assert instance_metrics['metrics'] == expected_metrics