Actor and songwriter George M. Cohan is impersonating President Franklin D. Roosevelt in the musical show I'd Rather Be Right, by George S. Kaufman and Moss Hart, when he is summoned to meet the President at the White House.  In response to the president's questions, George tells him the story of his life.

George was born on the Fourth of July, 1878 to Jerry and Nellie Cohan, a pair of vaudeville actors.  A short time later, his sister Josie is born and soon the family is touring the country as "The Four Cohans."  The family gets a big break when they are hired to star in Peck's Bad Boy.

At thirteen, George, the star of the play, is a success, but his self-importance is responsible for losing the Cohans several bookings.  Several years later, George, now a young man, meets aspiring singer Mary when he is playing the part of an old man and she comes backstage to ask his sage advice about breaking into show business.  The Cohans and Mary, who soon learns George's real age, go to New York, where George tries to sell the songs he has written.

When he learns that The Four Cohans are losing work because of his reputation for imperious behavior, he pretends that his play has been sold so that the others will accept a booking without him.  Later, in a bar, George overhears Sam H. Harris talking with Schwab, a potential backer, and offers him his new musical, Little Johnny Jones.  Sam and George become partners and produce a number of plays that feature George's popular formula of success stories laced with patriotism.

In the meantime, George proposes to Mary, Josie becomes engaged, and the older Cohans buy a farm and retire.  It is the end of The Four Cohans and George takes this opportunity to write Popularity, a serious play.  It fails miserably, but news of its failure is wiped out of the papers by the sinking of the Lusitania by the Germans in 1915.

When the U.S. enters the war, George tries to enlist but, at thirty-nine, is too old to be a soldier.  Unable to fight, George writes the inspirational song "Over There."

After World War I, Cohan writes more shows.  Josie and Nellie die and then George's father Jerry dies.  Feeling his age, George dissolves his partnership with Sam so that he and Mary can take a much needed rest.  They travel to Europe and Asia, and end up on the Cohan farm.  George pretends to enjoy his life, but he hates being out of the limelight.  After a group of teenagers see George reading Variety and think that the headline "Stix Nix Hix Pix" is a form of jive talk, George realizes how much he still wants to be performing and gladly accepts Sam's offer to star in I'd Rather be Right.

The President has listened quietly to George's story and now presents him with the Congressional Medal of Honor for his songs "Over There" and "It's a Grand Old Flag."  George is the first actor to receive this honor, and he responds as he used to when he was with The Four Cohans, "My mother thanks you; my father thanks you; my sister thanks you; and I thank you."  When George leaves the White House, a parade of soldiers and a band march by singing "Over There," and George proudly joins them. 

Interested in seeing his life story bought to the screen, Legendary Broadway showman George M. Cohan approached Samuel Goldwyn.  The project was offered to Fred Astaire who declined, meanwhile Cagney's brother and buisness manager Bill was searching for a story with real American flavor. Among the reasons to remove the taint that was attached to Cagney's reputation, which had been scarred by his so called radical activities in the thirties when he was a Roosevelt liberal. A friend of Cagney's who had been in a show with Cohan convinced him that Cagney would be perfect to portray him on film.  Cohan then approached  Warners with the project retaining rights to casting approval as well as screenplay.

The studio spared no expense in bringing the flag-waving biography of Cohan to the screen.  Cagney was in his element as George M. and delivered a finely-etched portrayal of the man and the entertainer. He rehearsed with Johnny Boyle who had worked with Cohan and had staged dances for him.  It was from Boyle that Cagney learned the stiff-legged technique and the run up the side proscenium arch. The production was superb in every aspect, and the cast was flawless down to the last member of the chorus. The film was nominated for eight academy awards and won three, including best actor for Cagney. The Broadway opening sold first-night tickets for war bonds. The cheapest tickets were sold for $25. The eighty-eight best seats went for $25,000. The total take, $5,750,000, was donated to the U.S. Treasury Department.