diff --git a/packages/react-debug-tools/src/ReactDebugHooks.js b/packages/react-debug-tools/src/ReactDebugHooks.js
index f30489b7f655f..9c310723b2605 100644
--- a/packages/react-debug-tools/src/ReactDebugHooks.js
+++ b/packages/react-debug-tools/src/ReactDebugHooks.js
@@ -739,11 +739,11 @@ function useHostTransitionStatus(): TransitionStatus {
 }
 
 function useResourceEffect(
-  create: () => mixed,
+  create: () => {...} | void | null,
   createDeps: Array<mixed> | void | null,
-  update: ((resource: mixed) => void) | void,
+  update: ((resource: {...} | void | null) => void) | void,
   updateDeps: Array<mixed> | void | null,
-  destroy: ((resource: mixed) => void) | void,
+  destroy: ((resource: {...} | void | null) => void) | void,
 ) {
   nextHook();
   hookLog.push({
diff --git a/packages/react-reconciler/src/ReactFiberCallUserSpace.js b/packages/react-reconciler/src/ReactFiberCallUserSpace.js
index a1b86c7560a2a..dd7beecd93582 100644
--- a/packages/react-reconciler/src/ReactFiberCallUserSpace.js
+++ b/packages/react-reconciler/src/ReactFiberCallUserSpace.js
@@ -183,7 +183,7 @@ export const callComponentWillUnmountInDEV: (
 const callCreate = {
   'react-stack-bottom-frame': function (
     effect: Effect,
-  ): (() => void) | mixed | void {
+  ): (() => void) | {...} | void | null {
     if (!enableUseResourceEffectHook) {
       if (effect.resourceKind != null) {
         if (__DEV__) {
diff --git a/packages/react-reconciler/src/ReactFiberCommitEffects.js b/packages/react-reconciler/src/ReactFiberCommitEffects.js
index 6873bdf9e7a63..a8e08721eed5f 100644
--- a/packages/react-reconciler/src/ReactFiberCommitEffects.js
+++ b/packages/react-reconciler/src/ReactFiberCommitEffects.js
@@ -274,6 +274,7 @@ export function commitHookEffectListMount(
                 addendum =
                   ' You returned null. If your effect does not require clean ' +
                   'up, return undefined (or nothing).';
+                // $FlowFixMe (@poteto) this check is safe on arbitrary non-null/void objects
               } else if (typeof destroy.then === 'function') {
                 addendum =
                   '\n\nIt looks like you wrote ' +
@@ -1036,10 +1037,10 @@ function safelyCallDestroy(
 function safelyCallDestroyWithResource(
   current: Fiber,
   nearestMountedAncestor: Fiber | null,
-  destroy: mixed => void,
-  resource: mixed,
+  destroy: ({...}) => void,
+  resource: {...},
 ) {
-  const destroy_ = resource == null ? destroy : destroy.bind(null, resource);
+  const destroy_ = destroy.bind(null, resource);
   if (__DEV__) {
     runWithFiberInDEV(
       current,
@@ -1050,6 +1051,7 @@ function safelyCallDestroyWithResource(
     );
   } else {
     try {
+      // $FlowFixMe(incompatible-call) Already bound to resource
       destroy_();
     } catch (error) {
       captureCommitPhaseError(current, nearestMountedAncestor, error);
diff --git a/packages/react-reconciler/src/ReactFiberHooks.js b/packages/react-reconciler/src/ReactFiberHooks.js
index f3a581a97476a..9d97710003317 100644
--- a/packages/react-reconciler/src/ReactFiberHooks.js
+++ b/packages/react-reconciler/src/ReactFiberHooks.js
@@ -205,8 +205,8 @@ export type Hook = {
 // the additional memory and we can follow up with performance
 // optimizations later.
 type EffectInstance = {
-  resource: mixed,
-  destroy: void | (() => void) | ((resource: mixed) => void),
+  resource: {...} | void | null,
+  destroy: void | (() => void) | ((resource: {...} | void | null) => void),
 };
 
 export const ResourceEffectIdentityKind: 0 = 0;
@@ -229,7 +229,7 @@ export type ResourceEffectIdentity = {
   resourceKind: typeof ResourceEffectIdentityKind,
   tag: HookFlags,
   inst: EffectInstance,
-  create: () => mixed,
+  create: () => {...} | void | null,
   deps: Array<mixed> | void | null,
   next: Effect,
 };
@@ -237,7 +237,7 @@ export type ResourceEffectUpdate = {
   resourceKind: typeof ResourceEffectUpdateKind,
   tag: HookFlags,
   inst: EffectInstance,
-  update: ((resource: mixed) => void) | void,
+  update: ((resource: {...} | void | null) => void) | void,
   deps: Array<mixed> | void | null,
   next: Effect,
   identity: ResourceEffectIdentity,
@@ -2540,9 +2540,9 @@ function pushResourceEffect(
   identityTag: HookFlags,
   updateTag: HookFlags,
   inst: EffectInstance,
-  create: () => mixed,
+  create: () => {...} | void | null,
   createDeps: Array<mixed> | void | null,
-  update: ((resource: mixed) => void) | void,
+  update: ((resource: {...} | void | null) => void) | void,
   updateDeps: Array<mixed> | void | null,
 ): Effect {
   const effectIdentity: ResourceEffectIdentity = {
@@ -2694,11 +2694,11 @@ function updateEffect(
 }
 
 function mountResourceEffect(
-  create: () => mixed,
+  create: () => {...} | void | null,
   createDeps: Array<mixed> | void | null,
-  update: ((resource: mixed) => void) | void,
+  update: ((resource: {...} | void | null) => void) | void,
   updateDeps: Array<mixed> | void | null,
-  destroy: ((resource: mixed) => void) | void,
+  destroy: ((resource: {...} | void | null) => void) | void,
 ) {
   if (
     __DEV__ &&
@@ -2730,11 +2730,11 @@ function mountResourceEffect(
 function mountResourceEffectImpl(
   fiberFlags: Flags,
   hookFlags: HookFlags,
-  create: () => mixed,
+  create: () => {...} | void | null,
   createDeps: Array<mixed> | void | null,
-  update: ((resource: mixed) => void) | void,
+  update: ((resource: {...} | void | null) => void) | void,
   updateDeps: Array<mixed> | void | null,
-  destroy: ((resource: mixed) => void) | void,
+  destroy: ((resource: {...} | void | null) => void) | void,
 ) {
   const hook = mountWorkInProgressHook();
   currentlyRenderingFiber.flags |= fiberFlags;
@@ -2752,11 +2752,11 @@ function mountResourceEffectImpl(
 }
 
 function updateResourceEffect(
-  create: () => mixed,
+  create: () => {...} | void | null,
   createDeps: Array<mixed> | void | null,
-  update: ((resource: mixed) => void) | void,
+  update: ((resource: {...} | void | null) => void) | void,
   updateDeps: Array<mixed> | void | null,
-  destroy: ((resource: mixed) => void) | void,
+  destroy: ((resource: {...} | void | null) => void) | void,
 ) {
   updateResourceEffectImpl(
     PassiveEffect,
@@ -2772,11 +2772,11 @@ function updateResourceEffect(
 function updateResourceEffectImpl(
   fiberFlags: Flags,
   hookFlags: HookFlags,
-  create: () => mixed,
+  create: () => {...} | void | null,
   createDeps: Array<mixed> | void | null,
-  update: ((resource: mixed) => void) | void,
+  update: ((resource: {...} | void | null) => void) | void,
   updateDeps: Array<mixed> | void | null,
-  destroy: ((resource: mixed) => void) | void,
+  destroy: ((resource: {...} | void | null) => void) | void,
 ) {
   const hook = updateWorkInProgressHook();
   const effect: Effect = hook.memoizedState;
@@ -4245,11 +4245,11 @@ if (__DEV__) {
   if (enableUseResourceEffectHook) {
     (HooksDispatcherOnMountInDEV: Dispatcher).useResourceEffect =
       function useResourceEffect(
-        create: () => mixed,
+        create: () => {...} | void | null,
         createDeps: Array<mixed> | void | null,
-        update: ((resource: mixed) => void) | void,
+        update: ((resource: {...} | void | null) => void) | void,
         updateDeps: Array<mixed> | void | null,
-        destroy: ((resource: mixed) => void) | void,
+        destroy: ((resource: {...} | void | null) => void) | void,
       ): void {
         currentHookNameInDev = 'useResourceEffect';
         mountHookTypesDev();
@@ -4433,11 +4433,11 @@ if (__DEV__) {
   if (enableUseResourceEffectHook) {
     (HooksDispatcherOnMountWithHookTypesInDEV: Dispatcher).useResourceEffect =
       function useResourceEffect(
-        create: () => mixed,
+        create: () => {...} | void | null,
         createDeps: Array<mixed> | void | null,
-        update: ((resource: mixed) => void) | void,
+        update: ((resource: {...} | void | null) => void) | void,
         updateDeps: Array<mixed> | void | null,
-        destroy: ((resource: mixed) => void) | void,
+        destroy: ((resource: {...} | void | null) => void) | void,
       ): void {
         currentHookNameInDev = 'useResourceEffect';
         updateHookTypesDev();
@@ -4620,11 +4620,11 @@ if (__DEV__) {
   if (enableUseResourceEffectHook) {
     (HooksDispatcherOnUpdateInDEV: Dispatcher).useResourceEffect =
       function useResourceEffect(
-        create: () => mixed,
+        create: () => {...} | void | null,
         createDeps: Array<mixed> | void | null,
-        update: ((resource: mixed) => void) | void,
+        update: ((resource: {...} | void | null) => void) | void,
         updateDeps: Array<mixed> | void | null,
-        destroy: ((resource: mixed) => void) | void,
+        destroy: ((resource: {...} | void | null) => void) | void,
       ) {
         currentHookNameInDev = 'useResourceEffect';
         updateHookTypesDev();
@@ -4807,11 +4807,11 @@ if (__DEV__) {
   if (enableUseResourceEffectHook) {
     (HooksDispatcherOnRerenderInDEV: Dispatcher).useResourceEffect =
       function useResourceEffect(
-        create: () => mixed,
+        create: () => {...} | void | null,
         createDeps: Array<mixed> | void | null,
-        update: ((resource: mixed) => void) | void,
+        update: ((resource: {...} | void | null) => void) | void,
         updateDeps: Array<mixed> | void | null,
-        destroy: ((resource: mixed) => void) | void,
+        destroy: ((resource: {...} | void | null) => void) | void,
       ) {
         currentHookNameInDev = 'useResourceEffect';
         updateHookTypesDev();
@@ -5019,11 +5019,11 @@ if (__DEV__) {
   if (enableUseResourceEffectHook) {
     (InvalidNestedHooksDispatcherOnMountInDEV: Dispatcher).useResourceEffect =
       function useResourceEffect(
-        create: () => mixed,
+        create: () => {...} | void | null,
         createDeps: Array<mixed> | void | null,
-        update: ((resource: mixed) => void) | void,
+        update: ((resource: {...} | void | null) => void) | void,
         updateDeps: Array<mixed> | void | null,
-        destroy: ((resource: mixed) => void) | void,
+        destroy: ((resource: {...} | void | null) => void) | void,
       ): void {
         currentHookNameInDev = 'useResourceEffect';
         warnInvalidHookAccess();
@@ -5232,11 +5232,11 @@ if (__DEV__) {
   if (enableUseResourceEffectHook) {
     (InvalidNestedHooksDispatcherOnUpdateInDEV: Dispatcher).useResourceEffect =
       function useResourceEffect(
-        create: () => mixed,
+        create: () => {...} | void | null,
         createDeps: Array<mixed> | void | null,
-        update: ((resource: mixed) => void) | void,
+        update: ((resource: {...} | void | null) => void) | void,
         updateDeps: Array<mixed> | void | null,
-        destroy: ((resource: mixed) => void) | void,
+        destroy: ((resource: {...} | void | null) => void) | void,
       ) {
         currentHookNameInDev = 'useResourceEffect';
         warnInvalidHookAccess();
@@ -5445,11 +5445,11 @@ if (__DEV__) {
   if (enableUseResourceEffectHook) {
     (InvalidNestedHooksDispatcherOnRerenderInDEV: Dispatcher).useResourceEffect =
       function useResourceEffect(
-        create: () => mixed,
+        create: () => {...} | void | null,
         createDeps: Array<mixed> | void | null,
-        update: ((resource: mixed) => void) | void,
+        update: ((resource: {...} | void | null) => void) | void,
         updateDeps: Array<mixed> | void | null,
-        destroy: ((resource: mixed) => void) | void,
+        destroy: ((resource: {...} | void | null) => void) | void,
       ) {
         currentHookNameInDev = 'useResourceEffect';
         warnInvalidHookAccess();
diff --git a/packages/react-reconciler/src/ReactInternalTypes.js b/packages/react-reconciler/src/ReactInternalTypes.js
index 0c5504cab468e..e31b7cefd1ed7 100644
--- a/packages/react-reconciler/src/ReactInternalTypes.js
+++ b/packages/react-reconciler/src/ReactInternalTypes.js
@@ -398,11 +398,11 @@ export type Dispatcher = {
   useEffectEvent?: <Args, F: (...Array<Args>) => mixed>(callback: F) => F,
   // TODO: Non-nullable once `enableUseResourceEffectHook` is on everywhere.
   useResourceEffect?: (
-    create: () => mixed,
+    create: () => {...} | void | null,
     createDeps: Array<mixed> | void | null,
-    update: ((resource: mixed) => void) | void,
+    update: ((resource: {...} | void | null) => void) | void,
     updateDeps: Array<mixed> | void | null,
-    destroy: ((resource: mixed) => void) | void,
+    destroy: ((resource: {...} | void | null) => void) | void,
   ) => void,
   useInsertionEffect(
     create: () => (() => void) | void,
diff --git a/packages/react/src/ReactHooks.js b/packages/react/src/ReactHooks.js
index 32f49268880f0..ff45b5415c416 100644
--- a/packages/react/src/ReactHooks.js
+++ b/packages/react/src/ReactHooks.js
@@ -202,11 +202,11 @@ export function useEffectEvent<Args, F: (...Array<Args>) => mixed>(
 }
 
 export function useResourceEffect(
-  create: () => mixed,
+  create: () => {...} | void | null,
   createDeps: Array<mixed> | void | null,
-  update: ((resource: mixed) => void) | void,
+  update: ((resource: {...} | void | null) => void) | void,
   updateDeps: Array<mixed> | void | null,
-  destroy: ((resource: mixed) => void) | void,
+  destroy: ((resource: {...} | void | null) => void) | void,
 ): void {
   if (!enableUseResourceEffectHook) {
     throw new Error('Not implemented.');