Warner Bros
O'Brien's first Warner Bros. movie was Bureau of Missing Persons (1933), starring Bette Davis. He went to RKO for Flaming Gold (1933) and MGM for Bombshell (1933), then Warners signed O'Brien to a long-term contract. He would remain with the studio until 1940, when he left after a dispute over the terms of his contract renewal.
O'Brien supported Dick Powell in College Coach (1933) and Joan Blondell in I've Got Your Number (1934). He was third lead to Barbara Stanwyck and Joel McCrea in Gambling Lady (1934), then was with Powell again in Twenty Million Sweethearts (1934).
Here Comes the Navy (1934) was O'Brien's first film with James Cagney, also under contract to Warners. The two originally met in 1926 and remained friends for almost six decades. After O'Brien's death, Cagney referred to him as his "dearest friend." O'Brien played the lead, a boxer, in The Personality Kid (1934), supported Powell in Flirtation Walk (1934) and was an auctioneer in I Sell Anything (1935).
Cagney and O'Brien were reteamed in Devil Dogs of the Air (1935). He was a critic in love with Dolores del Río in In Caliente (1935) and had the lead in the bio-pic Oil for the Lamps of China (1935), which he called "one of my favorite pictures." "That was a sweetheart," he said.
He and Cagney were in The Irish in Us (1935) then it was back to supporting Powell in Page Miss Glory (1935). He headlined a musical Stars Over Broadway (1935) then was back with Cagney for Howard Hawks' Ceiling Zero (1935). Cagney later sued Warners for billing O'Brien's name above his.
"Jimmy's grand to work with," said O'Brien in 1935. "You couldn't ask for a better partner but there's a limit to all that. I think one picture a year with Jimmy would be fine. But as it is I've been with him in every uniform – the army, the navy, the police, the marines, the air corps – and it's always a case of me falling for his girl or him falling for mine. It gets tiresome... I don't just want to be a fast-talking Charlie all my life."
Warners gave him some starring parts: I Married a Doctor (1936), Public Enemy's Wife (1936), China Clipper (1936), The Great O'Malley (1937), and Slim (1937) with Henry Fonda. He was Captain of the Guard (on special leave from the US Army) in San Quentin (1937) opposite Humphrey Bogart, romanced Blondell in Back in Circulation (1937) and was a veteran sailor in Submarine D-1 (1938).
O'Brien was pulled out of Swing Your Lady to co-star with Kay Francis in Women Are Like That (1938) and was back with Powell for Cowboy from Brooklyn (1938). He and Cagney reteamed for Boy Meets Girl (1938), and he was meant to be back with Powell in Garden of the Moon (1938), but Powell refused to do it – he was replaced by John Payne.
O'Brien had one of his best ever roles as the former street kid turned priest in Angels with Dirty Faces (1938) with Cagney. He was with Blondell in Off the Record (1939) and The Kid from Kokomo (1939), and co-starred with Gale Page in Indianapolis Speedway (1939).
He went over to Paramount for The Night of Nights (1939), part of a deal in which Warners bought the rights to The Old Maid from Paramount. He then made Slightly Honorable (1939) for United Artists.
Back at Warner Bros he was reunited with Cagney for The Fighting 69th (1940) then made Castle on the Hudson (1940) with Sheridan and John Garfield. He was a cop in 'Til We Meet Again (1940), with Cagney and Sheridan in Torrid Zone (1940). He co-starred with Garfield and Frances Farmer in Flowing Gold (1940).
O'Brien was then given his best known role, as the famous University of Notre Dame football coach Knute Rockne in Knute Rockne, All American (1940). In the film, he gave the speech to "win just one for the Gipper," referring to recently deceased football player, George Gipp, portrayed in the film by a young Ronald Reagan. Reagan later used this saying as a slogan for his campaign for president in 1980.
O'Brien was at a career peak. He was considered for the role of Alvin York in the film Sergeant York. From this high point, however, O'Brien left Warner Bros in July 1940.
