diff --git a/.changeset/migrate-chat-getThreadMessages-to-openapi.md b/.changeset/migrate-chat-getThreadMessages-to-openapi.md
new file mode 100644
index 0000000000000..999ca975edf05
--- /dev/null
+++ b/.changeset/migrate-chat-getThreadMessages-to-openapi.md
@@ -0,0 +1,6 @@
+---
+'@rocket.chat/meteor': minor
+'@rocket.chat/rest-typings': minor
+---
+
+Migrated chat.getThreadMessages endpoint to new OpenAPI pattern with AJV validation
diff --git a/apps/meteor/app/api/server/v1/chat.ts b/apps/meteor/app/api/server/v1/chat.ts
index a00d57e46ae72..8bb2e0cafe965 100644
--- a/apps/meteor/app/api/server/v1/chat.ts
+++ b/apps/meteor/app/api/server/v1/chat.ts
@@ -20,12 +20,12 @@ import {
 	isChatReactProps,
 	isChatGetDeletedMessagesProps,
 	isChatSyncThreadsListProps,
-	isChatGetThreadMessagesProps,
 	isChatSyncThreadMessagesProps,
 	isChatGetStarredMessagesProps,
 	isChatGetDiscussionsProps,
 	validateBadRequestErrorResponse,
 	validateUnauthorizedErrorResponse,
+	type PaginatedRequest,
 } from '@rocket.chat/rest-typings';
 import { escapeRegExp } from '@rocket.chat/string-helpers';
 import { Meteor } from 'meteor/meteor';
@@ -275,6 +275,44 @@ const isChatPinMessageProps = ajv.compile<ChatPinMessage>(ChatPinMessageSchema);
 
 const isChatUnpinMessageProps = ajv.compile<ChatUnpinMessage>(ChatUnpinMessageSchema);
 
+type ChatGetThreadMessages = PaginatedRequest<{
+	tmid: string;
+}>;
+
+const ChatGetThreadMessagesSchema = {
+	type: 'object',
+	properties: {
+		tmid: {
+			type: 'string',
+			minLength: 1,
+		},
+		count: {
+			type: 'number',
+			nullable: true,
+		},
+		offset: {
+			type: 'number',
+			nullable: true,
+		},
+		sort: {
+			type: 'string',
+			nullable: true,
+		},
+		query: {
+			type: 'string',
+			nullable: true,
+		},
+		fields: {
+			type: 'string',
+			nullable: true,
+		},
+	},
+	required: ['tmid'],
+	additionalProperties: false,
+};
+
+const isChatGetThreadMessagesLocalProps = ajv.compile<ChatGetThreadMessages>(ChatGetThreadMessagesSchema);
+
 const chatEndpoints = API.v1
 	.post(
 		'chat.pinMessage',
@@ -558,6 +596,76 @@ const chatEndpoints = API.v1
 
 			return API.v1.success();
 		},
+	)
+	.get(
+		'chat.getThreadMessages',
+		{
+			authRequired: true,
+			query: isChatGetThreadMessagesLocalProps,
+			response: {
+				200: ajv.compile<{
+					messages: IMessage[];
+					count: number;
+					offset: number;
+					total: number;
+					success: boolean;
+				}>({
+					type: 'object',
+					properties: {
+						messages: {
+							type: 'array',
+							items: { $ref: '#/components/schemas/IMessage' },
+						},
+						count: { type: 'number' },
+						offset: { type: 'number' },
+						total: { type: 'number' },
+						success: { type: 'boolean', enum: [true] },
+					},
+					required: ['messages', 'count', 'offset', 'total', 'success'],
+					additionalProperties: false,
+				}),
+				400: validateBadRequestErrorResponse,
+				401: validateUnauthorizedErrorResponse,
+			},
+		},
+		async function action() {
+			const { tmid } = this.queryParams;
+			const { query, fields, sort } = await this.parseJsonQuery();
+			const { offset, count } = await getPaginationItems(this.queryParams);
+
+			if (!settings.get('Threads_enabled')) {
+				throw new Meteor.Error('error-not-allowed', 'Threads Disabled');
+			}
+
+			const thread = await Messages.findOneById(tmid, { projection: { rid: 1 } });
+			if (!thread?.rid) {
+				throw new Meteor.Error('error-invalid-message', 'Invalid Message');
+			}
+			const user = await Users.findOneById(this.userId, { projection: { _id: 1 } });
+			const room = await Rooms.findOneById(thread.rid, { projection: { ...roomAccessAttributes, t: 1, _id: 1 } });
+
+			if (!room || !user || !(await canAccessRoomAsync(room, user))) {
+				throw new Meteor.Error('error-not-allowed', 'Not Allowed');
+			}
+			const { cursor, totalCount } = Messages.findPaginated(
+				{ ...query, tmid },
+				{
+					sort: sort || { ts: 1 },
+					skip: offset,
+					limit: count,
+					projection: fields,
+				},
+			);
+
+			const [messages, total] = await Promise.all([cursor.toArray(), totalCount]);
+
+			return API.v1.success({
+				messages,
+				count: messages.length,
+				offset,
+				total,
+			});
+		},
 	);
 
 API.v1.addRoute(
@@ -873,51 +981,6 @@ API.v1.addRoute(
 	},
 );
 
-API.v1.addRoute(
-	'chat.getThreadMessages',
-	{ authRequired: true, validateParams: isChatGetThreadMessagesProps },
-	{
-		async get() {
-			const { tmid } = this.queryParams;
-			const { query, fields, sort } = await this.parseJsonQuery();
-			const { offset, count } = await getPaginationItems(this.queryParams);
-
-			if (!settings.get('Threads_enabled')) {
-				throw new Meteor.Error('error-not-allowed', 'Threads Disabled');
-			}
-
-			const thread = await Messages.findOneById(tmid, { projection: { rid: 1 } });
-			if (!thread?.rid) {
-				throw new Meteor.Error('error-invalid-message', 'Invalid Message');
-			}
-			const user = await Users.findOneById(this.userId, { projection: { _id: 1 } });
-			const room = await Rooms.findOneById(thread.rid, { projection: { ...roomAccessAttributes, t: 1, _id: 1 } });
-
-			if (!room || !user || !(await canAccessRoomAsync(room, user))) {
-				throw new Meteor.Error('error-not-allowed', 'Not Allowed');
-			}
-			const { cursor, totalCount } = Messages.findPaginated(
-				{ ...query, tmid },
-				{
-					sort: sort || { ts: 1 },
-					skip: offset,
-					limit: count,
-					projection: fields,
-				},
-			);
-
-			const [messages, total] = await Promise.all([cursor.toArray(), totalCount]);
-
-			return API.v1.success({
-				messages,
-				count: messages.length,
-				offset,
-				total,
-			});
-		},
-	},
-);
-
 API.v1.addRoute(
 	'chat.syncThreadMessages',
 	{ authRequired: true, validateParams: isChatSyncThreadMessagesProps },
diff --git a/packages/rest-typings/src/v1/chat.ts b/packages/rest-typings/src/v1/chat.ts
index b52bba2d61ed5..cb4ff1d397a6f 100644
--- a/packages/rest-typings/src/v1/chat.ts
+++ b/packages/rest-typings/src/v1/chat.ts
@@ -673,36 +673,6 @@ const ChatSyncThreadMessagesSchema = {
 
 export const isChatSyncThreadMessagesProps = ajv.compile<ChatSyncThreadMessages>(ChatSyncThreadMessagesSchema);
 
-type ChatGetThreadMessages = PaginatedRequest<{
-	tmid: string;
-}>;
-
-const ChatGetThreadMessagesSchema = {
-	type: 'object',
-	properties: {
-		tmid: {
-			type: 'string',
-			minLength: 1,
-		},
-		count: {
-			type: 'number',
-			nullable: true,
-		},
-		offset: {
-			type: 'number',
-			nullable: true,
-		},
-		sort: {
-			type: 'string',
-			nullable: true,
-		},
-	},
-	required: ['tmid'],
-	additionalProperties: false,
-};
-
-export const isChatGetThreadMessagesProps = ajv.compile<ChatGetThreadMessages>(ChatGetThreadMessagesSchema);
-
 type ChatGetDeletedMessages = PaginatedRequest<{
 	roomId: IRoom['_id'];
 	since: string;
@@ -997,14 +967,6 @@ export type ChatEndpoints = {
 			};
 		};
 	};
-	'/v1/chat.getThreadMessages': {
-		GET: (params: ChatGetThreadMessages) => {
-			messages: IMessage[];
-			count: number;
-			offset: number;
-			total: number;
-		};
-	};
 	'/v1/chat.getDeletedMessages': {
 		GET: (params: ChatGetDeletedMessages) => {
 			messages: IMessage[];