However, by his mid-to-late 20s, he tired of his legal practice and turned a long term dream into a reality by becoming an actor on Broadway.

Mitchell's Broadway credits include Tide Rising (1936), All the King's Men (1928), One of the Family (1925), Spooks (1925), The Habitual Husband (1924), The Whole Town's Talking (1923), The School for Scandal (1923), Kempy (1921), The Hero (1920), The Champion (1920), and A Tailor-Made Man (1917).

Grant Michell often played the father of the heroine, businessmen, bank clerks or school principals.

[5] He usually played supporting characters, but also had a rare lead role in the B film comedy Father Is a Prince (1940).

He made many notable appearances in high-profile films such as Dinner At Eight (1933 David O. Selznick film), A Midsummer Night's Dream (1935, as Egeus), Mr. Smith Goes to Washington (1939, as a Washington senator), The Man Who Came to Dinner (1942, as the Stanley family's father), and Arsenic and Old Lace (1944, as Cary Grant's father-in-law Reverend Harper).