diff --git a/public/src/client/account/categories.js b/public/src/client/account/categories.js
index 8e162db809..bb6849b166 100644
--- a/public/src/client/account/categories.js
+++ b/public/src/client/account/categories.js
@@ -1,7 +1,7 @@
 'use strict';
 
 
-define('forum/account/categories', ['forum/account/header', 'alerts'], function (header, alerts) {
+define('forum/account/categories', ['forum/account/header', 'alerts', 'api'], function (header, alerts, api) {
 	const Categories = {};
 
 	Categories.init = function () {
@@ -11,36 +11,32 @@ define('forum/account/categories', ['forum/account/header', 'alerts'], function
 			handleIgnoreWatch(category.cid);
 		});
 
-		$('[component="category/watch/all"]').find('[component="category/watching"], [component="category/ignoring"], [component="category/notwatching"]').on('click', function () {
+		$('[component="category/watch/all"]').find('[component="category/watching"], [component="category/ignoring"], [component="category/notwatching"]').on('click', async (e) => {
 			const cids = [];
-			const state = $(this).attr('data-state');
+			const state = e.currentTarget.getAttribute('data-state');
+			const { uid } = ajaxify.data;
 			$('[data-parent-cid="0"]').each(function (index, el) {
 				cids.push($(el).attr('data-cid'));
 			});
 
-			socket.emit('categories.setWatchState', { cid: cids, state: state, uid: ajaxify.data.uid }, function (err, modified_cids) {
-				if (err) {
-					return alerts.error(err);
-				}
-				updateDropdowns(modified_cids, state);
-			});
+			let modified_cids = await Promise.all(cids.map(async cid => api.put(`/categories/${cid}/watch`, { state, uid })));
+			modified_cids = modified_cids
+				.reduce((memo, cur) => memo.concat(cur.modified), [])
+				.filter((cid, idx, arr) => arr.indexOf(cid) === idx);
+
+			updateDropdowns(modified_cids, state);
 		});
 	};
 
 	function handleIgnoreWatch(cid) {
 		const category = $('[data-cid="' + cid + '"]');
-		category.find('[component="category/watching"], [component="category/ignoring"], [component="category/notwatching"]').on('click', function () {
-			const $this = $(this);
-			const state = $this.attr('data-state');
+		category.find('[component="category/watching"], [component="category/ignoring"], [component="category/notwatching"]').on('click', async (e) => {
+			const state = e.currentTarget.getAttribute('data-state');
+			const { uid } = ajaxify.data;
 
-			socket.emit('categories.setWatchState', { cid: cid, state: state, uid: ajaxify.data.uid }, function (err, modified_cids) {
-				if (err) {
-					return alerts.error(err);
-				}
-				updateDropdowns(modified_cids, state);
-
-				alerts.success('[[category:' + state + '.message]]');
-			});
+			const { modified } = await api.put(`/categories/${cid}/watch`, { state, uid });
+			updateDropdowns(modified, state);
+			alerts.success('[[category:' + state + '.message]]');
 		});
 	}
 
diff --git a/public/src/client/category.js b/public/src/client/category.js
index a89620cb34..3aff45420e 100644
--- a/public/src/client/category.js
+++ b/public/src/client/category.js
@@ -69,7 +69,7 @@ define('forum/category', [
 			const $this = $(this);
 			const state = $this.attr('data-state');
 
-			socket.emit('categories.setWatchState', { cid: cid, state: state }, function (err) {
+			api.put(`/categories/${cid}/watch`, { state }, (err) => {
 				if (err) {
 					return alerts.error(err);
 				}
diff --git a/src/api/categories.js b/src/api/categories.js
index 28b2539a3a..442131b4fd 100644
--- a/src/api/categories.js
+++ b/src/api/categories.js
@@ -1,6 +1,7 @@
 'use strict';
 
 const categories = require('../categories');
+const topics = require('../topics');
 const events = require('../events');
 const user = require('../user');
 const groups = require('../groups');
@@ -84,6 +85,31 @@ categoriesAPI.getTopicCount = async (caller, { cid }) => {
 
 categoriesAPI.getPosts = async (caller, { cid }) => await categories.getRecentReplies(cid, caller.uid, 0, 4);
 
+categoriesAPI.setWatchState = async (caller, { cid, state, uid }) => {
+	let targetUid = caller.uid;
+	const cids = Array.isArray(cid) ? cid.map(cid => parseInt(cid, 10)) : [parseInt(cid, 10)];
+	if (uid) {
+		targetUid = uid;
+	}
+	await user.isAdminOrGlobalModOrSelf(caller.uid, targetUid);
+	const allCids = await categories.getAllCidsFromSet('categories:cid');
+	const categoryData = await categories.getCategoriesFields(allCids, ['cid', 'parentCid']);
+
+	// filter to subcategories of cid
+	let cat;
+	do {
+		cat = categoryData.find(c => !cids.includes(c.cid) && cids.includes(c.parentCid));
+		if (cat) {
+			cids.push(cat.cid);
+		}
+	} while (cat);
+
+	await user.setCategoryWatchState(targetUid, cids, state);
+	await topics.pushUnreadCount(targetUid);
+
+	return { cids };
+};
+
 categoriesAPI.getPrivileges = async (caller, { cid }) => {
 	await hasAdminPrivilege(caller.uid, 'privileges');
 
diff --git a/src/controllers/write/categories.js b/src/controllers/write/categories.js
index 8d4c0aebcf..e987b433ce 100644
--- a/src/controllers/write/categories.js
+++ b/src/controllers/write/categories.js
@@ -1,6 +1,7 @@
 'use strict';
 
 const categories = require('../../categories');
+const meta = require('../../meta');
 const api = require('../../api');
 
 const helpers = require('../helpers');
@@ -44,6 +45,24 @@ Categories.getPosts = async (req, res) => {
 	helpers.formatApiResponse(200, res, posts);
 };
 
+Categories.setWatchState = async (req, res) => {
+	const { cid } = req.params;
+	let { uid, state } = req.body;
+
+	if (req.method === 'DELETE') {
+		// DELETE is always setting state to system default in acp
+		state = categories.watchStates[meta.config.categoryWatchState];
+	} else if (Object.keys(categories.watchStates).includes(state)) {
+		state = categories.watchStates[state]; // convert to integer for backend processing
+	} else {
+		throw new Error('[[error:invalid-data]]');
+	}
+
+	const { cids: modified } = await api.categories.setWatchState(req, { cid, state, uid });
+
+	helpers.formatApiResponse(200, res, { modified });
+};
+
 Categories.getPrivileges = async (req, res) => {
 	const privilegeSet = await api.categories.getPrivileges(req, { cid: req.params.cid });
 	helpers.formatApiResponse(200, res, privilegeSet);
diff --git a/src/middleware/assert.js b/src/middleware/assert.js
index 553114f870..6c0f5ef72f 100644
--- a/src/middleware/assert.js
+++ b/src/middleware/assert.js
@@ -11,6 +11,7 @@ const nconf = require('nconf');
 const file = require('../file');
 const user = require('../user');
 const groups = require('../groups');
+const categories = require('../categories');
 const topics = require('../topics');
 const posts = require('../posts');
 const messaging = require('../messaging');
@@ -39,6 +40,14 @@ Assert.group = helpers.try(async (req, res, next) => {
 	next();
 });
 
+Assert.category = helpers.try(async (req, res, next) => {
+	if (!await categories.exists(req.params.cid)) {
+		return controllerHelpers.formatApiResponse(404, res, new Error('[[error:no-category]]'));
+	}
+
+	next();
+});
+
 Assert.topic = helpers.try(async (req, res, next) => {
 	if (!await topics.exists(req.params.tid)) {
 		return controllerHelpers.formatApiResponse(404, res, new Error('[[error:no-topic]]'));
diff --git a/src/routes/write/categories.js b/src/routes/write/categories.js
index 44a3020863..f1e2f39504 100644
--- a/src/routes/write/categories.js
+++ b/src/routes/write/categories.js
@@ -19,6 +19,9 @@ module.exports = function () {
 	setupApiRoute(router, 'get', '/:cid/count', [...middlewares], controllers.write.categories.getTopicCount);
 	setupApiRoute(router, 'get', '/:cid/posts', [...middlewares], controllers.write.categories.getPosts);
 
+	setupApiRoute(router, 'put', '/:cid/watch', [...middlewares, middleware.assert.category], controllers.write.categories.setWatchState);
+	setupApiRoute(router, 'delete', '/:cid/watch', [...middlewares, middleware.assert.category], controllers.write.categories.setWatchState);
+
 	setupApiRoute(router, 'get', '/:cid/privileges', [...middlewares], controllers.write.categories.getPrivileges);
 	setupApiRoute(router, 'put', '/:cid/privileges/:privilege', [...middlewares, middleware.checkRequired.bind(null, ['member'])], controllers.write.categories.setPrivilege);
 	setupApiRoute(router, 'delete', '/:cid/privileges/:privilege', [...middlewares, middleware.checkRequired.bind(null, ['member'])], controllers.write.categories.setPrivilege);
diff --git a/src/socket.io/categories.js b/src/socket.io/categories.js
index aea08cdfa2..e2b647f71a 100644
--- a/src/socket.io/categories.js
+++ b/src/socket.io/categories.js
@@ -112,12 +112,16 @@ SocketCategories.getSelectCategories = async function (socket) {
 };
 
 SocketCategories.setWatchState = async function (socket, data) {
+	sockets.warnDeprecated(socket, 'PUT/DELETE /api/v3/categories/:cid/watch');
+
 	if (!data || !data.cid || !data.state) {
 		throw new Error('[[error:invalid-data]]');
 	}
-	return await ignoreOrWatch(async (uid, cids) => {
-		await user.setCategoryWatchState(uid, cids, categories.watchStates[data.state]);
-	}, socket, data);
+
+	data.state = categories.watchStates[data.state];
+
+	await api.categories.setWatchState(socket, data);
+	return data.cid;
 };
 
 SocketCategories.watch = async function (socket, data) {