Richardson began her career in regional theatre at the West Yorkshire Playhouse in Leeds, and, in 1984, at the Open Air Theatre in London's Regent's Park, when she appeared in A Midsummer Night's Dream with Ralph Fiennes and Richard E. Grant. Her first professional work in London's West End was in a revival of Anton Chekhov's The Seagull in 1985. This production also featured her mother, Vanessa Redgrave. Soon afterward she starred in a London stage production of High Society, adapted from the Cole Porter film. She made her Broadway debut in 1993, in the title role of Anna Christie, which is where she met future husband Liam Neeson. In 1998, she played the role of Sally Bowles in Sam Mendes' revival of Cabaret on Broadway, for which she won the Tony Award for Best Actress in a Musical. The following year she returned to Broadway in Closer, for which she was nominated for the Drama Desk Award for Outstanding Featured Actress in a Play, and in 2005, she appeared again with the Roundabout, this time as Blanche DuBois in the revival of Tennessee Williams's A Streetcar Named Desire, opposite John C. Reilly as Stanley Kowalski. In January 2009, two months before her death, Richardson played the role of Desirée in a concert production of Stephen Sondheim's A Little Night Music, with her mother Vanessa Redgrave who played Mme. Armfeldt. At the time of Richardson's death, the pair were preparing to co-star in a Broadway revival of the musical.