Actor and dramatist, O'Brien lived for a time in America. While performing in Dublin the handsome young actor was recruited by David Garrick to replace Henry Woodward, and on 3 October 1758 he made his début at Drury Lane, as Captain Brazen in Farquhar's The Recruiting Officer. Between 1758 and 1764 he played comic parts, specialising in ‘harlequin’ and fine gentlemen. In 1764 he married Lady Susan Fox-Strangways, to whom William Byrne's engraving E26 Niagara Falls after Wilson was dedicated.
