diff --git a/CHANGES.md b/CHANGES.md
index 4b406255173..3e456b50373 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -8,6 +8,7 @@ Fixed Issues:
 * [#13118](http://dev.ckeditor.com/ticket/13118): Fixed: The [`editor.getSelectedHtml()`](http://docs.ckeditor.com/#!/api/CKEDITOR.editor-method-getSelectedHtml) method throws error when called in the source mode.
 * [#13158](http://dev.ckeditor.com/ticket/13158): Fixed: Error after canceling dialog when creating a widget.
 * [#13197](http://dev.ckeditor.com/ticket/13197): Fixed: Linked inline image2's alignment class is not transferred to widget wrapper.
+* [#13199](http://dev.ckeditor.com/ticket/13199): Fixed: Embedsemantic does not support widget classes.
 * Toolbar configurators:
   * [#13185](http://dev.ckeditor.com/ticket/13185): Fixed: Wrong position of the suggestion box if there is not enough space below the caret.
   * [#13138](http://dev.ckeditor.com/ticket/13138): Fixed: The "Toggle empty elements" button label is unclear.
diff --git a/plugins/embedsemantic/plugin.js b/plugins/embedsemantic/plugin.js
index 29133ed868c..8323a99ff44 100644
--- a/plugins/embedsemantic/plugin.js
+++ b/plugins/embedsemantic/plugin.js
@@ -68,14 +68,23 @@
 						data.loadOnReady = true;
 						div = new CKEDITOR.htmlParser.element( 'div' );
 						element.replaceWith( div );
+
+						// Transfer widget classes from data to widget element (#13199).
+						div.attributes[ 'class' ] = element.attributes[ 'class' ];
+
 						return div;
 					}
 				},
 
-				downcast: function() {
+				downcast: function( element ) {
 					var ret = new CKEDITOR.htmlParser.element( 'oembed' );
 					ret.add( new CKEDITOR.htmlParser.text( this.data.url ) );
 
+					// Transfer widget classes from widget element back to data (#13199).
+					if ( element.attributes[ 'class' ] ) {
+						ret.attributes[ 'class' ] = element.attributes[ 'class' ];
+					}
+
 					return ret;
 				}
 			}, true );
diff --git a/tests/plugins/embed/integration.js b/tests/plugins/embed/integration.js
index e85bfbdba99..8008ceaa7b7 100644
--- a/tests/plugins/embed/integration.js
+++ b/tests/plugins/embed/integration.js
@@ -8,13 +8,36 @@
 bender.editors = {
 	classic: {
 		name: 'editor_classic',
-		creator: 'replace'
+		creator: 'replace',
+		config: {
+			extraAllowedContent: 'div(a,b,c)'
+		}
 	}
 };
 
+var obj2Array = widgetTestsTools.obj2Array;
+var classes2Array = widgetTestsTools.classes2Array;
+
 embedTools.mockJsonp();
 
-var tcs = {};
+var tcs = {
+	'test support for widget classes': function() {
+		var bot = this.editorBots.classic,
+			editor = bot.editor,
+			data = '<div class="a b c" data-oembed-url="http://foo.jpg">' +
+					'<img alt="image" src="//foo.jpg" style="max-width:100%;" />' +
+				'</div>';
+
+		bot.setData( data, function() {
+			wait( function() {
+				arrayAssert.itemsAreSame( [ 'a', 'b', 'c' ],
+					classes2Array( obj2Array( editor.widgets.instances )[ 0 ].getClasses() ).sort(), 'classes transfered from data to widget.element' );
+
+				assert.areSame( data, bot.getData( 1, 1 ), 'classes transfered from widget.element back to data' );
+			}, 100 );
+		} );
+	}
+};
 
 widgetTestsTools.addTests( tcs, {
 	name: 'basic',
diff --git a/tests/plugins/embedsemantic/integration.js b/tests/plugins/embedsemantic/integration.js
index e21665ed05f..8a577e7f35f 100644
--- a/tests/plugins/embedsemantic/integration.js
+++ b/tests/plugins/embedsemantic/integration.js
@@ -8,11 +8,15 @@
 bender.editors = {
 	classic: {
 		name: 'editor_classic',
-		creator: 'replace'
+		creator: 'replace',
+		config: {
+			extraAllowedContent: 'oembed(a,b,c)'
+		}
 	}
 };
 
 var obj2Array = widgetTestsTools.obj2Array;
+var classes2Array = widgetTestsTools.classes2Array;
 
 embedTools.mockJsonp();
 
@@ -81,6 +85,20 @@ var tcs = {
 				assert.isFalse( loadContentSpy.called, 'widget.loadContent was not called on undo' );
 			}, 100 );
 		} );
+	},
+
+	'test support for widget classes': function() {
+		var bot = this.editorBots.classic,
+			editor = bot.editor;
+
+		bot.setData( '<p>x</p><oembed class="a c b">http://widget/classes</oembed><p>x</p>', function() {
+			wait( function() {
+				arrayAssert.itemsAreSame( [ 'a', 'b', 'c' ],
+					classes2Array( obj2Array( editor.widgets.instances )[ 0 ].getClasses() ).sort(), 'classes transfered from data to widget.element' );
+
+				assert.areSame( '<p>x</p><oembed class="a b c">http://widget/classes</oembed><p>x</p>', bot.getData(), 'classes transfered from widget.element back to data' );
+			}, 100 );
+		} );
 	}
 };