diff --git a/.changeset/fair-cats-destroy.md b/.changeset/fair-cats-destroy.md
new file mode 100644
index 00000000000..7dfb74955a9
--- /dev/null
+++ b/.changeset/fair-cats-destroy.md
@@ -0,0 +1,6 @@
+---
+"@rocket.chat/meteor": patch
+"@rocket.chat/model-typings": patch
+---
+
+When setting a room as read-only, do not allow previously unmuted users to send messages.
diff --git a/apps/meteor/app/federation/server/endpoints/dispatch.js b/apps/meteor/app/federation/server/endpoints/dispatch.js
index cf9e91b44af..59ffcb0f342 100644
--- a/apps/meteor/app/federation/server/endpoints/dispatch.js
+++ b/apps/meteor/app/federation/server/endpoints/dispatch.js
@@ -457,8 +457,8 @@ const eventHandlers = {
 			// Denormalize user
 			const denormalizedUser = normalizers.denormalizeUser(user);
 
-			// Mute user
-			await Rooms.unmuteUsernameByRoomId(roomId, denormalizedUser.username);
+			// Unmute user
+			await Rooms.unmuteMutedUsernameByRoomId(roomId, denormalizedUser.username);
 		}
 
 		return eventResult;
diff --git a/apps/meteor/server/methods/muteUserInRoom.ts b/apps/meteor/server/methods/muteUserInRoom.ts
index eac10e320ea..90e4b61a57e 100644
--- a/apps/meteor/server/methods/muteUserInRoom.ts
+++ b/apps/meteor/server/methods/muteUserInRoom.ts
@@ -65,7 +65,11 @@ export const muteUserInRoom = async (fromId: string, data: { rid: IRoom['_id'];
 
 	await callbacks.run('beforeMuteUser', { mutedUser, fromUser }, room);
 
-	await Rooms.muteUsernameByRoomId(data.rid, mutedUser.username);
+	if (room.ro) {
+		await Rooms.muteReadOnlyUsernameByRoomId(data.rid, mutedUser.username);
+	} else {
+		await Rooms.muteUsernameByRoomId(data.rid, mutedUser.username);
+	}
 
 	await Message.saveSystemMessage('user-muted', data.rid, mutedUser.username, fromUser);
 
diff --git a/apps/meteor/server/methods/unmuteUserInRoom.ts b/apps/meteor/server/methods/unmuteUserInRoom.ts
index 991e66840ca..d9e65815fd1 100644
--- a/apps/meteor/server/methods/unmuteUserInRoom.ts
+++ b/apps/meteor/server/methods/unmuteUserInRoom.ts
@@ -65,7 +65,11 @@ export const unmuteUserInRoom = async (fromId: string, data: { rid: IRoom['_id']
 
 	await callbacks.run('beforeUnmuteUser', { unmutedUser, fromUser }, room);
 
-	await Rooms.unmuteUsernameByRoomId(data.rid, unmutedUser.username);
+	if (room.ro) {
+		await Rooms.unmuteReadOnlyUsernameByRoomId(data.rid, unmutedUser.username);
+	} else {
+		await Rooms.unmuteMutedUsernameByRoomId(data.rid, unmutedUser.username);
+	}
 
 	await Message.saveSystemMessage('user-unmuted', data.rid, unmutedUser.username, fromUser);
 
diff --git a/apps/meteor/server/models/raw/Rooms.ts b/apps/meteor/server/models/raw/Rooms.ts
index 10fad0f436e..9dad0fa60da 100644
--- a/apps/meteor/server/models/raw/Rooms.ts
+++ b/apps/meteor/server/models/raw/Rooms.ts
@@ -1708,9 +1708,33 @@ export class RoomsRaw extends BaseRaw<IRoom> implements IRoomsModel {
 		return this.updateOne(query, update);
 	}
 
-	unmuteUsernameByRoomId(_id: IRoom['_id'], username: IUser['username']): Promise<UpdateResult> {
+	muteReadOnlyUsernameByRoomId(_id: IRoom['_id'], username: IUser['username']): Promise<UpdateResult> {
+		const query: Filter<IRoom> = { _id, ro: true };
+
+		const update: UpdateFilter<IRoom> = {
+			$pull: {
+				unmuted: username,
+			},
+		};
+
+		return this.updateOne(query, update);
+	}
+
+	unmuteMutedUsernameByRoomId(_id: IRoom['_id'], username: IUser['username']): Promise<UpdateResult> {
 		const query: Filter<IRoom> = { _id };
 
+		const update: UpdateFilter<IRoom> = {
+			$pull: {
+				muted: username,
+			},
+		};
+
+		return this.updateOne(query, update);
+	}
+
+	unmuteReadOnlyUsernameByRoomId(_id: string, username: string): Promise<UpdateResult> {
+		const query: Filter<IRoom> = { _id, ro: true };
+
 		const update: UpdateFilter<IRoom> = {
 			$pull: {
 				muted: username,
diff --git a/packages/model-typings/src/models/IRoomsModel.ts b/packages/model-typings/src/models/IRoomsModel.ts
index a0053d7ea7b..de0cf9d10f9 100644
--- a/packages/model-typings/src/models/IRoomsModel.ts
+++ b/packages/model-typings/src/models/IRoomsModel.ts
@@ -251,7 +251,9 @@ export interface IRoomsModel extends IBaseModel<IRoom> {
 	): Promise<UpdateResult>;
 	setCustomFieldsById(rid: string, customFields: Record<string, any>): Promise<UpdateResult>;
 	muteUsernameByRoomId(rid: string, username: string): Promise<UpdateResult>;
-	unmuteUsernameByRoomId(rid: string, username: string): Promise<UpdateResult>;
+	muteReadOnlyUsernameByRoomId(rid: string, username: string): Promise<UpdateResult>;
+	unmuteMutedUsernameByRoomId(rid: string, username: string): Promise<UpdateResult>;
+	unmuteReadOnlyUsernameByRoomId(rid: string, username: string): Promise<UpdateResult>;
 	saveFeaturedById(rid: string, featured: boolean): Promise<UpdateResult>;
 	saveDefaultById(rid: string, defaultValue: boolean): Promise<UpdateResult>;
 	saveFavoriteById(rid: string, favorite: boolean, defaultValue: boolean): Promise<UpdateResult>;