For 23 episodes, from 1996–1998, she appeared in Ballykissangel in the role of Assumpta Fitzgerald, the landlady of the village's only pub, Fitzgerald's. She is no friend of the church – until Father Peter Clifford (Stephen Tompkinson) is posted to the village from his previous parish in Manchester. She also continued this role for a Comic Relief special of The Vicar of Dibley, and in a Father Ted special. Kirwan's performance in Ballykissangel won her the National TV Award for Best Actress in 1996, and the Irish Post Award for Best Irish Entertainer in 1997. In 1998, she starred alongside Christopher Eccleston in the Michael Winterbottom film With or Without You as Belfast girl Rosie Boyd.