 He married on 4 July 1789 to Juliana Lucy Annesley (died 10 October 1833), daughter of Arthur Annesley, 1st Earl of Mountnorris, 8th Viscount Valentia.In 1788, Maxwell-Barry stood as Member of Parliament for Cavan County, however was declared not duly elected.He later represented Doneraile in the Irish House of Commons from 1792 to 1798, and subsequently Newtown Limavady until the Act of Union in 1801.