His first appearance on the stage is at the Theatre Royal, Smock Alley, Dublin, on the February 5, 1744, and this engagement at once increases its prosperity. His first London appearance is made in 1746 as Othello at the Theatre Royal, Drury Lane. Here his talents are speedily recognized, and in Hamlet and Macbeth he alternates with David Garrick, arousing the latter’s jealousy by his success as Romeo. This results in his leaving Drury Lane for the Covent Garden Theatre in 1750, accompanied by Susannah Maria Cibber, his Juliet. Both houses simultaneously put on Romeo and Juliet for a series of rival performances, and Barry’s Romeo is preferred by the critics to Garrick’s.
In 1758, Barry opens the Crow Street theatre in Dublin, and later a new theatre in Cork. He stages many successful productions but seems to have lived beyond his means. In 1767 he returns to London to play at the Haymarket Theatre, then under the management of Samuel Foote. As his second wife, he marries in 1768 the actress Ann Street Dancer, and he and Mrs. Barry play under Garrick’s management, Barry appearing in 1767, after ten years absence from the London stage, in Othello, his greatest part. In 1774 they both move to Covent Garden, where Barry remains until his death on January 10, 1777.