diff --git a/packages/react-client/src/forks/ReactFlightClientConfig.custom.js b/packages/react-client/src/forks/ReactFlightClientConfig.custom.js
index 45a47a8c1405f..3add5988aab8a 100644
--- a/packages/react-client/src/forks/ReactFlightClientConfig.custom.js
+++ b/packages/react-client/src/forks/ReactFlightClientConfig.custom.js
@@ -23,7 +23,7 @@
 // So `$$$config` looks like a global variable, but it's
 // really an argument to a top-level wrapping function.
 
-declare var $$$config: any;
+declare const $$$config: any;
 
 export opaque type ModuleLoading = mixed;
 export opaque type SSRModuleMap = mixed;
diff --git a/packages/react-devtools-extensions/flow-typed/jest.js b/packages/react-devtools-extensions/flow-typed/jest.js
index 066655593abb3..cdbe32bee7ba6 100644
--- a/packages/react-devtools-extensions/flow-typed/jest.js
+++ b/packages/react-devtools-extensions/flow-typed/jest.js
@@ -960,7 +960,7 @@ declare function beforeAll(
 ): void;
 
 /** A context for grouping tests together */
-declare var describe: {
+declare const describe: {
   /**
    * Creates a block that groups together several related tests in one "test suite"
    */
@@ -991,7 +991,7 @@ declare var describe: {
 };
 
 /** An individual test unit */
-declare var it: {
+declare const it: {
   /**
    * An individual test unit
    *
@@ -1079,15 +1079,15 @@ declare function fit(
   timeout?: number
 ): void;
 /** An individual test unit */
-declare var test: typeof it;
+declare const test: typeof it;
 /** A disabled group of tests */
-declare var xdescribe: typeof describe;
+declare const xdescribe: typeof describe;
 /** A focused group of tests */
-declare var fdescribe: typeof describe;
+declare const fdescribe: typeof describe;
 /** A disabled individual test */
-declare var xit: typeof it;
+declare const xit: typeof it;
 /** A disabled individual test */
-declare var xtest: typeof it;
+declare const xtest: typeof it;
 
 type JestPrettyFormatColors = {
   comment: {close: string, open: string},
@@ -1139,7 +1139,7 @@ type JestPrettyFormatPlugin = {
 type JestPrettyFormatPlugins = Array<JestPrettyFormatPlugin>;
 
 /** The expect function is used every time you want to test a value */
-declare var expect: {
+declare const expect: {
   /** The object that you want to make assertions against */
   (
     value: any
@@ -1173,4 +1173,4 @@ declare var expect: {
 };
 
 /** Holds all functions related to manipulating test runner */
-declare var jest: JestObjectType;
+declare const jest: JestObjectType;
diff --git a/packages/react-native-renderer/src/ReactNativeTypes.js b/packages/react-native-renderer/src/ReactNativeTypes.js
index f02b921b6ce7a..0b44ef7f81e39 100644
--- a/packages/react-native-renderer/src/ReactNativeTypes.js
+++ b/packages/react-native-renderer/src/ReactNativeTypes.js
@@ -125,7 +125,7 @@ export type NativeMethods = $ReadOnly<{|
 |}>;
 
 // This validates that INativeMethods and NativeMethods stay in sync using Flow!
-declare var ensureNativeMethodsAreSynced: NativeMethods;
+declare const ensureNativeMethodsAreSynced: NativeMethods;
 (ensureNativeMethodsAreSynced: INativeMethods);
 
 export type HostComponent<T> = AbstractComponent<T, $ReadOnly<NativeMethods>>;
diff --git a/packages/react-reconciler/src/ReactFiberDevToolsHook.js b/packages/react-reconciler/src/ReactFiberDevToolsHook.js
index abf56e90fabc2..dead0fda4691c 100644
--- a/packages/react-reconciler/src/ReactFiberDevToolsHook.js
+++ b/packages/react-reconciler/src/ReactFiberDevToolsHook.js
@@ -41,7 +41,7 @@ import {
 import {setSuppressWarning} from 'shared/consoleWithStackDev';
 import {disableLogs, reenableLogs} from 'shared/ConsolePatchingDev';
 
-declare var __REACT_DEVTOOLS_GLOBAL_HOOK__: Object | void;
+declare const __REACT_DEVTOOLS_GLOBAL_HOOK__: Object | void;
 
 let rendererID = null;
 let injectedHook = null;
diff --git a/packages/react-reconciler/src/forks/ReactFiberConfig.custom.js b/packages/react-reconciler/src/forks/ReactFiberConfig.custom.js
index c2c6fd21e5987..5bf200268ef85 100644
--- a/packages/react-reconciler/src/forks/ReactFiberConfig.custom.js
+++ b/packages/react-reconciler/src/forks/ReactFiberConfig.custom.js
@@ -23,7 +23,7 @@
 // So `$$$config` looks like a global variable, but it's
 // really an argument to a top-level wrapping function.
 
-declare var $$$config: any;
+declare const $$$config: any;
 export opaque type Type = mixed; // eslint-disable-line no-undef
 export opaque type Props = mixed; // eslint-disable-line no-undef
 export opaque type Container = mixed; // eslint-disable-line no-undef
diff --git a/packages/react-server/src/ReactFlightServerConfigBundlerCustom.js b/packages/react-server/src/ReactFlightServerConfigBundlerCustom.js
index e11c154d05f32..00578a4da2459 100644
--- a/packages/react-server/src/ReactFlightServerConfigBundlerCustom.js
+++ b/packages/react-server/src/ReactFlightServerConfigBundlerCustom.js
@@ -7,7 +7,7 @@
  * @flow
  */
 
-declare var $$$config: any;
+declare const $$$config: any;
 
 export opaque type ClientManifest = mixed;
 export opaque type ClientReference<T> = mixed; // eslint-disable-line no-unused-vars
diff --git a/packages/react-server/src/forks/ReactFizzConfig.custom.js b/packages/react-server/src/forks/ReactFizzConfig.custom.js
index cf1e05a54165d..495a74fb18656 100644
--- a/packages/react-server/src/forks/ReactFizzConfig.custom.js
+++ b/packages/react-server/src/forks/ReactFizzConfig.custom.js
@@ -26,7 +26,7 @@
 import type {Request} from 'react-server/src/ReactFizzServer';
 import type {TransitionStatus} from 'react-reconciler/src/ReactFiberConfig';
 
-declare var $$$config: any;
+declare const $$$config: any;
 export opaque type Destination = mixed; // eslint-disable-line no-undef
 export opaque type RenderState = mixed;
 export opaque type HoistableState = mixed;
diff --git a/packages/react-server/src/forks/ReactServerStreamConfig.custom.js b/packages/react-server/src/forks/ReactServerStreamConfig.custom.js
index e372e8903f856..22cd6551c0b28 100644
--- a/packages/react-server/src/forks/ReactServerStreamConfig.custom.js
+++ b/packages/react-server/src/forks/ReactServerStreamConfig.custom.js
@@ -23,7 +23,7 @@
 // So `$$$config` looks like a global variable, but it's
 // really an argument to a top-level wrapping function.
 
-declare var $$$config: any;
+declare const $$$config: any;
 export opaque type Destination = mixed; // eslint-disable-line no-undef
 
 export opaque type PrecomputedChunk = mixed; // eslint-disable-line no-undef
diff --git a/packages/scheduler/src/forks/SchedulerNative.js b/packages/scheduler/src/forks/SchedulerNative.js
index a7370d92a650b..3832cbc69753e 100644
--- a/packages/scheduler/src/forks/SchedulerNative.js
+++ b/packages/scheduler/src/forks/SchedulerNative.js
@@ -32,7 +32,7 @@ type NativeSchedulerType = {
   unstable_now: () => DOMHighResTimeStamp,
 };
 
-declare var nativeRuntimeScheduler: void | NativeSchedulerType;
+declare const nativeRuntimeScheduler: void | NativeSchedulerType;
 
 export const unstable_UserBlockingPriority: PriorityLevel =
   typeof nativeRuntimeScheduler !== 'undefined'
diff --git a/scripts/flow/environment.js b/scripts/flow/environment.js
index 255ed4a2b99ba..cba4dd5e61566 100644
--- a/scripts/flow/environment.js
+++ b/scripts/flow/environment.js
@@ -9,25 +9,25 @@
 
 /* eslint-disable */
 
-declare var __PROFILE__: boolean;
-declare var __UMD__: boolean;
-declare var __EXPERIMENTAL__: boolean;
-declare var __VARIANT__: boolean;
+declare const __PROFILE__: boolean;
+declare const __UMD__: boolean;
+declare const __EXPERIMENTAL__: boolean;
+declare const __VARIANT__: boolean;
 
-declare var __REACT_DEVTOOLS_GLOBAL_HOOK__: any; /*?{
+declare const __REACT_DEVTOOLS_GLOBAL_HOOK__: any; /*?{
   inject: ?((stuff: Object) => void)
 };*/
 
-declare var globalThis: Object;
+declare const globalThis: Object;
 
-declare var queueMicrotask: (fn: Function) => void;
-declare var reportError: (error: mixed) => void;
-declare var AggregateError: Class<Error>;
+declare const queueMicrotask: (fn: Function) => void;
+declare const reportError: (error: mixed) => void;
+declare const AggregateError: Class<Error>;
 
-declare var FinalizationRegistry: any;
+declare const FinalizationRegistry: any;
 
 declare module 'create-react-class' {
-  declare var exports: React$CreateClass;
+  declare const exports: React$CreateClass;
 }
 
 // Flow hides the props of React$Element, this overrides it to unhide
@@ -43,7 +43,7 @@ declare opaque type React$Element<
   +ref: any,
 };
 
-declare var trustedTypes: {
+declare const trustedTypes: {
   isHTML: (value: any) => boolean,
   isScript: (value: any) => boolean,
   isScriptURL: (value: any) => boolean,
@@ -89,22 +89,22 @@ declare module 'EventListener' {
 }
 
 declare function __webpack_chunk_load__(id: string): Promise<mixed>;
-declare var __webpack_require__: ((id: string) => any) & {
+declare const __webpack_require__: ((id: string) => any) & {
   u: string => string,
 };
 
 declare function __turbopack_load__(id: string): Promise<mixed>;
-declare var __turbopack_require__: ((id: string) => any) & {
+declare const __turbopack_require__: ((id: string) => any) & {
   u: string => string,
 };
 
 declare module 'fs/promises' {
-  declare var access: (path: string, mode?: number) => Promise<void>;
-  declare var lstat: (
+  declare const access: (path: string, mode?: number) => Promise<void>;
+  declare const lstat: (
     path: string,
     options?: ?{bigint?: boolean},
   ) => Promise<mixed>;
-  declare var readdir: (
+  declare const readdir: (
     path: string,
     options?:
       | ?string
@@ -113,7 +113,7 @@ declare module 'fs/promises' {
           withFileTypes?: ?boolean,
         },
   ) => Promise<Buffer>;
-  declare var readFile: (
+  declare const readFile: (
     path: string,
     options?:
       | ?string
@@ -121,7 +121,7 @@ declare module 'fs/promises' {
           encoding?: ?string,
         },
   ) => Promise<Buffer>;
-  declare var readlink: (
+  declare const readlink: (
     path: string,
     options?:
       | ?string
@@ -129,7 +129,7 @@ declare module 'fs/promises' {
           encoding?: ?string,
         },
   ) => Promise<mixed>;
-  declare var realpath: (
+  declare const realpath: (
     path: string,
     options?:
       | ?string
@@ -137,13 +137,13 @@ declare module 'fs/promises' {
           encoding?: ?string,
         },
   ) => Promise<mixed>;
-  declare var stat: (
+  declare const stat: (
     path: string,
     options?: ?{bigint?: boolean},
   ) => Promise<mixed>;
 }
 declare module 'pg' {
-  declare var Pool: (options: mixed) => {
+  declare const Pool: (options: mixed) => {
     query: (query: string, values?: Array<mixed>) => void,
   };
 }
@@ -320,7 +320,7 @@ declare class AsyncLocalStorage<T> {
   enterWith(store: T): void;
 }
 
-declare var async_hooks: {
+declare const async_hooks: {
   createHook(callbacks: any): any,
   executionAsyncId(): number,
 };
@@ -332,7 +332,7 @@ declare module 'node:worker_threads' {
   }
 }
 
-declare var Bun: {
+declare const Bun: {
   hash(
     input: string | $TypedArray | DataView | ArrayBuffer | SharedArrayBuffer,
   ): number,
diff --git a/scripts/flow/react-devtools.js b/scripts/flow/react-devtools.js
index 86968330ec31f..361ca168190ef 100644
--- a/scripts/flow/react-devtools.js
+++ b/scripts/flow/react-devtools.js
@@ -9,12 +9,12 @@
 
 /* eslint-disable no-unused-vars */
 
-declare var __EXTENSION__: boolean;
-declare var __TEST__: boolean;
+declare const __EXTENSION__: boolean;
+declare const __TEST__: boolean;
 
-declare var DARK_MODE_DIMMED_WARNING_COLOR: string;
-declare var DARK_MODE_DIMMED_ERROR_COLOR: string;
-declare var DARK_MODE_DIMMED_LOG_COLOR: string;
-declare var LIGHT_MODE_DIMMED_WARNING_COLOR: string;
-declare var LIGHT_MODE_DIMMED_ERROR_COLOR: string;
-declare var LIGHT_MODE_DIMMED_LOG_COLOR: string;
+declare const DARK_MODE_DIMMED_WARNING_COLOR: string;
+declare const DARK_MODE_DIMMED_ERROR_COLOR: string;
+declare const DARK_MODE_DIMMED_LOG_COLOR: string;
+declare const LIGHT_MODE_DIMMED_WARNING_COLOR: string;
+declare const LIGHT_MODE_DIMMED_ERROR_COLOR: string;
+declare const LIGHT_MODE_DIMMED_LOG_COLOR: string;
diff --git a/scripts/flow/react-native-host-hooks.js b/scripts/flow/react-native-host-hooks.js
index e1b8b0ca72a17..9c86a8ffeb95c 100644
--- a/scripts/flow/react-native-host-hooks.js
+++ b/scripts/flow/react-native-host-hooks.js
@@ -49,21 +49,21 @@ declare module 'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface'
   ): boolean;
   declare export function deepFreezeAndThrowOnMutationInDev<T>(obj: T): T;
   declare export function flattenStyle(style: any): any;
-  declare export var RCTEventEmitter: {
+  declare export const RCTEventEmitter: {
     register: (eventEmitter: mixed) => void,
     ...
   };
-  declare export var TextInputState: {
+  declare export const TextInputState: {
     blurTextInput: (object: any) => void,
     focusTextInput: (object: any) => void,
     ...
   };
-  declare export var ReactFiberErrorDialog: {
+  declare export const ReactFiberErrorDialog: {
     showErrorDialog: (error: __CapturedError) => boolean,
     ...
   };
-  declare export var Platform: {OS: string, ...};
-  declare export var UIManager: {
+  declare export const Platform: {OS: string, ...};
+  declare export const UIManager: {
     customBubblingEventTypes: Object,
     customDirectEventTypes: Object,
     createView: (
@@ -123,15 +123,15 @@ declare module 'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface'
     ) => void,
     ...
   };
-  declare export var legacySendAccessibilityEvent: (
+  declare export const legacySendAccessibilityEvent: (
     reactTag: number,
     eventTypeName: string,
   ) => void;
-  declare export var BatchedBridge: {
+  declare export const BatchedBridge: {
     registerCallableModule: (name: string, module: Object) => void,
     ...
   };
-  declare export var ReactNativeViewConfigRegistry: {
+  declare export const ReactNativeViewConfigRegistry: {
     customBubblingEventTypes: Object,
     customDirectEventTypes: Object,
 
@@ -139,7 +139,7 @@ declare module 'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface'
     get: (name: string) => __ReactNativeBaseComponentViewConfig,
     ...
   };
-  declare export var RawEventEmitter: {
+  declare export const RawEventEmitter: {
     emit: (channel: string, event: RawEventEmitterEvent) => string,
     ...
   };
@@ -171,7 +171,7 @@ declare const RN$enableMicrotasksInReact: boolean;
 
 // This is needed for a short term solution.
 // See https://github.com/facebook/react/pull/15490 for more info
-declare var nativeFabricUIManager: {
+declare const nativeFabricUIManager: {
   createNode: (
     reactTag: number,
     viewName: string,
diff --git a/scripts/flow/xplat.js b/scripts/flow/xplat.js
index 9c458c2c8ef8c..61e3a5692f2e5 100644
--- a/scripts/flow/xplat.js
+++ b/scripts/flow/xplat.js
@@ -8,16 +8,16 @@
  */
 
 declare module 'ReactNativeInternalFeatureFlags' {
-  declare export var alwaysThrottleDisappearingFallbacks: boolean;
-  declare export var alwaysThrottleRetries: boolean;
-  declare export var consoleManagedByDevToolsDuringStrictMode: boolean;
-  declare export var enableAsyncActions: boolean;
-  declare export var enableComponentStackLocations: boolean;
-  declare export var enableDeferRootSchedulingToMicrotask: boolean;
-  declare export var enableInfiniteRenderLoopDetection: boolean;
-  declare export var enableRenderableContext: boolean;
-  declare export var enableUnifiedSyncLane: boolean;
-  declare export var enableUseRefAccessWarning: boolean;
-  declare export var passChildrenWhenCloningPersistedNodes: boolean;
-  declare export var useModernStrictMode: boolean;
+  declare export const alwaysThrottleDisappearingFallbacks: boolean;
+  declare export const alwaysThrottleRetries: boolean;
+  declare export const consoleManagedByDevToolsDuringStrictMode: boolean;
+  declare export const enableAsyncActions: boolean;
+  declare export const enableComponentStackLocations: boolean;
+  declare export const enableDeferRootSchedulingToMicrotask: boolean;
+  declare export const enableInfiniteRenderLoopDetection: boolean;
+  declare export const enableRenderableContext: boolean;
+  declare export const enableUnifiedSyncLane: boolean;
+  declare export const enableUseRefAccessWarning: boolean;
+  declare export const passChildrenWhenCloningPersistedNodes: boolean;
+  declare export const useModernStrictMode: boolean;
 }
diff --git a/scripts/jest/typescript/jest.d.ts b/scripts/jest/typescript/jest.d.ts
index 43aa392287e7c..57e93783665a7 100644
--- a/scripts/jest/typescript/jest.d.ts
+++ b/scripts/jest/typescript/jest.d.ts
@@ -1,16 +1,16 @@
-declare var __DEV__: boolean;
-declare var __TEST__: boolean;
-declare var __EXTENSION__: boolean;
+declare const __DEV__: boolean;
+declare const __TEST__: boolean;
+declare const __EXTENSION__: boolean;
 
 declare function afterEach(fn: any): any;
 declare function beforeEach(fn: any): any;
 declare function describe(name: string, fn: any): void;
-declare var it: {
+declare const it: {
   (name: string, fn: any): void;
   only: (name: string, fn: any) => void;
 }
 declare function expect(val: any): Expect;
-declare var jest: Jest;
+declare const jest: Jest;
 declare function pit(name: string, fn: any): void;
 declare function spyOnDev(obj: any, key: string): any;
 declare function spyOnDevAndProd(obj: any, key: string): any;
@@ -70,5 +70,5 @@ interface MockFunction {
   mockReturnValueOnce(value: any): MockFunction
 }
 
-declare var check: any;
-declare var gen: any;
+declare const check: any;
+declare const gen: any;