She had her first major stage success in George Kelly's Pulitzer-winning Craig's Wife in 1926. Kelly wrote a role especially for her in his next play, Daisy Mayme, which also was staged in 1926. She continued working in New York theater throughout the 1920s. In the 1930s and 1940s, Hull appeared in three Broadway hits, as a batty matriarch in You Can't Take It with You (1936), as a homicidal old lady in Arsenic and Old Lace (1941), and in Harvey (1944). The plays all had long runs, and took up ten years of Hull's career. Her last Broadway play, The Solid Gold Cadillac (1954–55), was later into a film version with the much younger Judy Holliday in the role.