diff --git a/spec/ParseServerRESTController.spec.js b/spec/ParseServerRESTController.spec.js
index 389f9f740a..a8636082b0 100644
--- a/spec/ParseServerRESTController.spec.js
+++ b/spec/ParseServerRESTController.spec.js
@@ -1,7 +1,8 @@
-const ParseServerRESTController = require('../lib/ParseServerRESTController')
-  .ParseServerRESTController;
+const ParseServerRESTController =
+  require('../lib/ParseServerRESTController').ParseServerRESTController;
 const ParseServer = require('../lib/ParseServer').default;
 const Parse = require('parse/node').Parse;
+const request = require('../lib/request');
 
 let RESTController;
 
@@ -163,9 +164,7 @@ describe('ParseServerRESTController', () => {
         const results = await query.find();
         expect(createSpy.calls.count()).toBe(2);
         for (let i = 0; i + 1 < createSpy.calls.length; i = i + 2) {
-          expect(createSpy.calls.argsFor(i)[3]).toBe(
-            createSpy.calls.argsFor(i + 1)[3]
-          );
+          expect(createSpy.calls.argsFor(i)[3]).toBe(createSpy.calls.argsFor(i + 1)[3]);
         }
         expect(results.map(result => result.get('key')).sort()).toEqual(['value1', 'value2']);
       });
@@ -610,6 +609,129 @@ describe('ParseServerRESTController', () => {
     }
   });
 
+  it('should strip undefined values from cloud function responses (with directAccess)', async () => {
+    Parse.Cloud.define('returnUndefinedValues', () => {
+      return {
+        definedKey: 'value',
+        undefinedKey: undefined,
+        nested: { a: 1, b: undefined },
+        arrayWithUndefined: [1, undefined, 3],
+      };
+    });
+
+    const res = await RESTController.request(
+      'POST',
+      '/functions/returnUndefinedValues',
+      {},
+      { useMasterKey: true }
+    );
+
+    expect(res.result.definedKey).toEqual('value');
+    expect(res.result.undefinedKey).toBeUndefined();
+    expect(Object.hasOwnProperty.call(res.result, 'undefinedKey')).toBe(false);
+    expect(res.result.nested.a).toEqual(1);
+    expect(Object.hasOwnProperty.call(res.result.nested, 'b')).toBe(false);
+    expect(res.result.arrayWithUndefined).toEqual([1, null, 3]);
+  });
+
+  it('should strip undefined values from cloud function responses (without directAccess)', async () => {
+    Parse.Cloud.define('returnUndefinedValuesHTTP', () => {
+      return {
+        definedKey: 'value',
+        undefinedKey: undefined,
+        nested: { a: 1, b: undefined },
+        arrayWithUndefined: [1, undefined, 3],
+      };
+    });
+
+    const serverURL = 'http://localhost:8378/1';
+    const headers = {
+      'Content-Type': 'application/json',
+      'X-Parse-Application-Id': Parse.applicationId,
+      'X-Parse-Master-Key': Parse.masterKey,
+    };
+
+    const res = await request({
+      method: 'POST',
+      headers,
+      url: `${serverURL}/functions/returnUndefinedValuesHTTP`,
+      body: {},
+    });
+
+    const result = res.data.result;
+
+    expect(result.definedKey).toEqual('value');
+    expect(result.undefinedKey).toBeUndefined();
+    expect(Object.hasOwnProperty.call(result, 'undefinedKey')).toBe(false);
+    expect(result.nested.a).toEqual(1);
+    expect(Object.hasOwnProperty.call(result.nested, 'b')).toBe(false);
+    expect(result.arrayWithUndefined).toEqual([1, null, 3]);
+  });
+
+  it('should call toJSON() on cloud function results with a custom toJSON (with directAccess)', async () => {
+    Parse.Cloud.define('returnCustomToJSON', () => {
+      return {
+        raw: 'should be replaced',
+        undefinedKey: undefined,
+        toJSON() {
+          return { serialized: true, undefinedKey: undefined, nested: { b: undefined, c: 2 } };
+        },
+      };
+    });
+
+    const res = await RESTController.request(
+      'POST',
+      '/functions/returnCustomToJSON',
+      {},
+      { useMasterKey: true }
+    );
+
+    // toJSON() must be invoked (matching JSON.stringify in HTTP mode), not treated
+    // as a plain record, and undefined keys inside its result must be stripped.
+    expect(res.result.serialized).toEqual(true);
+    expect(res.result.raw).toBeUndefined();
+    expect(Object.hasOwnProperty.call(res.result, 'raw')).toBe(false);
+    expect(Object.hasOwnProperty.call(res.result, 'undefinedKey')).toBe(false);
+    expect(Object.hasOwnProperty.call(res.result, 'toJSON')).toBe(false);
+    expect(res.result.nested.c).toEqual(2);
+    expect(Object.hasOwnProperty.call(res.result.nested, 'b')).toBe(false);
+  });
+
+  it('should call toJSON() on cloud function results with a custom toJSON (without directAccess)', async () => {
+    Parse.Cloud.define('returnCustomToJSONHTTP', () => {
+      return {
+        raw: 'should be replaced',
+        undefinedKey: undefined,
+        toJSON() {
+          return { serialized: true, undefinedKey: undefined, nested: { b: undefined, c: 2 } };
+        },
+      };
+    });
+
+    const serverURL = 'http://localhost:8378/1';
+    const headers = {
+      'Content-Type': 'application/json',
+      'X-Parse-Application-Id': Parse.applicationId,
+      'X-Parse-Master-Key': Parse.masterKey,
+    };
+
+    const res = await request({
+      method: 'POST',
+      headers,
+      url: `${serverURL}/functions/returnCustomToJSONHTTP`,
+      body: {},
+    });
+
+    const result = res.data.result;
+    expect(result.serialized).toEqual(true);
+    expect(result.raw).toBeUndefined();
+    expect(Object.hasOwnProperty.call(result, 'raw')).toBe(false);
+    expect(Object.hasOwnProperty.call(result, 'undefinedKey')).toBe(false);
+    expect(Object.hasOwnProperty.call(result, 'toJSON')).toBe(false);
+    expect(result.nested.c).toEqual(2);
+    expect(Object.hasOwnProperty.call(result.nested, 'b')).toBe(false);
+  });
+
   it('ensures sessionTokens are properly handled', async () => {
     const user = await Parse.User.signUp('user', 'pass');
     const sessionToken = user.getSessionToken();
@@ -750,16 +872,23 @@ describe('ParseServerRESTController', () => {
       data: { alert: 'We return status!' },
       where: { deviceType: 'ios' },
     };
-    const res = await RESTController.request('POST', 'batch', {
-      requests: [{
-        method: 'POST',
-        path: '/push',
-        body: payload,
-      }],
-    }, {
-      useMasterKey: true,
-      returnStatus: true,
-    });
+    const res = await RESTController.request(
+      'POST',
+      'batch',
+      {
+        requests: [
+          {
+            method: 'POST',
+            path: '/push',
+            body: payload,
+          },
+        ],
+      },
+      {
+        useMasterKey: true,
+        returnStatus: true,
+      }
+    );
     const pushStatusId = res[0]._headers['X-Parse-Push-Status-Id'];
     expect(pushStatusId).toBeDefined();
 
@@ -767,6 +896,192 @@ describe('ParseServerRESTController', () => {
     expect(result.id).toBe(pushStatusId);
   });
 
+  it('should strip undefined values from GET query params with directAccess', async () => {
+    let capturedWhere;
+    Parse.Cloud.beforeFind('QueryStripObject', req => {
+      capturedWhere = req.query.toJSON().where;
+    });
+
+    const uniqueValue = `directAccess_${Date.now()}`;
+    await RESTController.request('POST', '/classes/QueryStripObject', {
+      presentField: uniqueValue,
+      absentField: undefined,
+    });
+
+    // If undefined values in "where" are not stripped, they would become null
+    // and the query would filter for absentField: null, failing to match the object.
+    const getRes = await RESTController.request('GET', '/classes/QueryStripObject', {
+      where: { presentField: uniqueValue, absentField: undefined },
+    });
+
+    expect(getRes.results.length).toBe(1);
+    expect(getRes.results[0].presentField).toBe(uniqueValue);
+    expect(capturedWhere.presentField).toBe(uniqueValue);
+    expect('absentField' in capturedWhere).toBe(false);
+  });
+
+  it('should strip undefined values from GET query params without directAccess (HTTP mode)', async () => {
+    let capturedWhere;
+    Parse.Cloud.beforeFind('QueryStripObjectHTTP', req => {
+      capturedWhere = req.query.toJSON().where;
+    });
+
+    const serverURL = 'http://localhost:8378/1';
+    const headers = {
+      'Content-Type': 'application/json',
+      'X-Parse-Application-Id': Parse.applicationId,
+      'X-Parse-Master-Key': Parse.masterKey,
+    };
+    const uniqueValue = `httpMode_${Date.now()}`;
+
+    await request({
+      method: 'POST',
+      headers,
+      url: `${serverURL}/classes/QueryStripObjectHTTP`,
+      body: { presentField: uniqueValue, absentField: undefined },
+    });
+
+    // In HTTP mode, JSON.stringify naturally strips undefined values from the where clause.
+    const getRes = await request({
+      method: 'GET',
+      headers,
+      url: `${serverURL}/classes/QueryStripObjectHTTP?where=${encodeURIComponent(JSON.stringify({ presentField: uniqueValue, absentField: undefined }))}`,
+    });
+
+    expect(getRes.data.results.length).toBe(1);
+    expect(getRes.data.results[0].presentField).toBe(uniqueValue);
+    expect(capturedWhere.presentField).toBe(uniqueValue);
+    expect('absentField' in capturedWhere).toBe(false);
+  });
+
+  it('should not convert undefined values to null on update with directAccess', async () => {
+    const createRes = await RESTController.request('POST', '/classes/MyObject', {
+      presentField: 'hello',
+    });
+    expect(createRes.objectId).toBeDefined();
+
+    await RESTController.request('PUT', `/classes/MyObject/${createRes.objectId}`, {
+      presentField: 'updated',
+      absentField: undefined,
+      nested: { absentField: undefined, presentField: 'value' },
+    });
+
+    const getRes = await RESTController.request('GET', `/classes/MyObject/${createRes.objectId}`);
+
+    expect(getRes.presentField).toBe('updated');
+    expect(getRes.absentField).toBeUndefined();
+    expect('absentField' in getRes).toBe(false);
+    expect(getRes.nested).toBeDefined();
+    expect(getRes.nested.presentField).toBe('value');
+    expect('absentField' in getRes.nested).toBe(false);
+  });
+
+  it('should not convert undefined values to null on create with directAccess', async () => {
+    const createRes = await RESTController.request('POST', '/classes/MyObject', {
+      presentField: 'hello',
+      absentField: undefined,
+    });
+    expect(createRes.objectId).toBeDefined();
+
+    const getRes = await RESTController.request('GET', `/classes/MyObject/${createRes.objectId}`);
+
+    expect(getRes.presentField).toBe('hello');
+    expect(getRes.absentField).toBeUndefined();
+    expect('absentField' in getRes).toBe(false);
+  });
+
+  it('should not throw when request body is frozen (directAccess)', async () => {
+    const createRes = await RESTController.request('POST', '/classes/MyObject', {
+      presentField: 'hello',
+    });
+    expect(createRes.objectId).toBeDefined();
+
+    const body = Object.freeze({
+      presentField: 'updated',
+      absentField: undefined,
+      nested: Object.freeze({ absentField: undefined, presentField: 'value' }),
+      arrayWithUndefined: Object.freeze([1, undefined, 3]),
+    });
+
+    await RESTController.request('PUT', `/classes/MyObject/${createRes.objectId}`, body);
+
+    const getRes = await RESTController.request('GET', `/classes/MyObject/${createRes.objectId}`);
+
+    expect(getRes.presentField).toBe('updated');
+    expect('absentField' in getRes).toBe(false);
+    expect(getRes.nested.presentField).toBe('value');
+    expect('absentField' in getRes.nested).toBe(false);
+    expect(getRes.arrayWithUndefined).toEqual([1, null, 3]);
+  });
+
+  it('should not convert undefined values to null on update without directAccess (HTTP mode)', async () => {
+    const serverURL = 'http://localhost:8378/1';
+    const headers = {
+      'Content-Type': 'application/json',
+      'X-Parse-Application-Id': Parse.applicationId,
+      'X-Parse-Master-Key': Parse.masterKey,
+    };
+
+    const createRes = await request({
+      method: 'POST',
+      headers,
+      url: `${serverURL}/classes/MyObject`,
+      body: { presentField: 'hello' },
+    });
+    expect(createRes.data.objectId).toBeDefined();
+
+    await request({
+      method: 'PUT',
+      headers,
+      url: `${serverURL}/classes/MyObject/${createRes.data.objectId}`,
+      body: {
+        presentField: 'updated',
+        absentField: undefined,
+        nested: { absentField: undefined, presentField: 'value' },
+      },
+    });
+
+    const getRes = await request({
+      method: 'GET',
+      headers,
+      url: `${serverURL}/classes/MyObject/${createRes.data.objectId}`,
+    });
+
+    expect(getRes.data.presentField).toBe('updated');
+    expect(getRes.data.absentField).toBeUndefined();
+    expect('absentField' in getRes.data).toBe(false);
+    expect(getRes.data.nested).toBeDefined();
+    expect(getRes.data.nested.presentField).toBe('value');
+    expect('absentField' in getRes.data.nested).toBe(false);
+  });
+
+  it('should not convert undefined values to null on create without directAccess (HTTP mode)', async () => {
+    const serverURL = 'http://localhost:8378/1';
+    const headers = {
+      'Content-Type': 'application/json',
+      'X-Parse-Application-Id': Parse.applicationId,
+      'X-Parse-Master-Key': Parse.masterKey,
+    };
+
+    const createRes = await request({
+      method: 'POST',
+      headers,
+      url: `${serverURL}/classes/MyObject`,
+      body: { presentField: 'hello', absentField: undefined },
+    });
+    expect(createRes.data.objectId).toBeDefined();
+
+    const getRes = await request({
+      method: 'GET',
+      headers,
+      url: `${serverURL}/classes/MyObject/${createRes.data.objectId}`,
+    });
+
+    expect(getRes.data.presentField).toBe('hello');
+    expect(getRes.data.absentField).toBeUndefined();
+    expect('absentField' in getRes.data).toBe(false);
+  });
+
   it('handles an object ID without alphanumeric characters', async () => {
     await reconfigureServer({ allowCustomObjectId: true });
     await RESTController.request('POST', '/classes/TestObject', { objectId: '-', key: 'value' });
diff --git a/src/ParseServerRESTController.js b/src/ParseServerRESTController.js
index 3f1c4dd4bf..de4bbabdc3 100644
--- a/src/ParseServerRESTController.js
+++ b/src/ParseServerRESTController.js
@@ -29,6 +29,29 @@ function getAuth(options = {}, config) {
   });
 }
 
+function stripUndefined(obj) {
+  if (obj === null || obj === undefined || typeof obj !== 'object') {
+    return obj;
+  }
+  // Match JSON.stringify semantics: objects with a toJSON() method serialize
+  // through it before undefined stripping. Date/RegExp are pre-encoded by the
+  // SDK/router, but a custom toJSON on a cloud function result reaches here
+  // (FunctionsRouter uses Parse._encode, not JSON.stringify).
+  if (typeof obj.toJSON === 'function') {
+    return stripUndefined(obj.toJSON());
+  }
+  if (Array.isArray(obj)) {
+    return obj.map(item => (item === undefined ? null : stripUndefined(item)));
+  }
+  const result = {};
+  for (const key of Object.keys(obj)) {
+    if (obj[key] !== undefined) {
+      result[key] = stripUndefined(obj[key]);
+    }
+  }
+  return result;
+}
+
 function ParseServerRESTController(applicationId, router) {
   function handleRequest(method, path, data = {}, options = {}, config) {
     // Store the arguments, for later use if internal fails
@@ -125,7 +148,7 @@ function ParseServerRESTController(applicationId, router) {
       }
       getAuth(options, config).then(auth => {
         const request = {
-          body: data,
+          body: stripUndefined(data),
           config,
           auth,
           info: {
@@ -134,7 +157,7 @@ function ParseServerRESTController(applicationId, router) {
             installationId: options.installationId,
             context: requestContext,
           },
-          query,
+          query: query ? stripUndefined(query) : query,
         };
         return Promise.resolve()
           .then(() => {
@@ -143,10 +166,11 @@ function ParseServerRESTController(applicationId, router) {
           .then(
             resp => {
               const { response, status, headers = {} } = resp;
+              const strippedResponse = stripUndefined(response);
               if (options.returnStatus) {
-                resolve({ ...response, _status: status, _headers: headers });
+                resolve({ ...strippedResponse, _status: status, _headers: headers });
               } else {
-                resolve(response);
+                resolve(strippedResponse);
               }
             },
             err => {