He was of a theatrical family, his parents being actors. He made his first stage appearance at Drury Lane in 1807. After three years in Dublin, he was again at Drury Lane until he went to the United States in 1818, appearing as Macbeth at the Park Theatre, New York. He settled permanently in New York City in 1852. The first Wallack's theatre was an old one, renamed, at the corner of Broome Street and Broadway. The second, at 13th Street and Broadway, he built himself. His son opened the third and last Wallack's Theatre in 1882.
Wallack was an actor of the old school. Thackeray praised his performance as Shylock, and Joseph Jefferson his Don Caesar de Bazan. He married the daughter of John Henry Johnstone (1749-1828), a popular tenor and stage Irishman; she died in 1851. Their son, John Lester Wallack was also a famous actor.