Born William Joseph Shields, he was originally an insurance salesman, he came into acting later in life. He got his start performing the works of Sean O'Casey at Dublin's famed Abbey Theatre, including Juno and the Paycock and The Plough and the Stars. He quickly found his niche as comic relief. His earliest film roles were reprising his roles O'Casey's plays for film. He was a favorite of John Ford who cast him in many of his classic films including How Green Was My Valley and The Quiet Man. His half-brother Arthur Shields, was also an actor and appeared in many of Ford's films too.
Barry Fitzgerald would retire from acting in 1959 and moved to Dublin.
- The Plough and the Stars (1936) — first collaboration with John Ford
- Bringing Up Baby (1938)
- Four Men and a Prayer (1938 — second collaboration with John Ford
- The Long Voyage Home (1940) — third collaboration with John Ford
- The Sea Wolf (1941)
- How Green Was My Valley (1941) — fourth collaboration with John Ford
- Going My Way (1944)
- None but the Lonely Heart (1944)
- And Then There Were None (1945)
- The Naked City (1948)
- The Quiet Man (1952) — fifth and final collaboration with John Ford