Based in part on several of Buster's own experiences in the army, the script (by Richard Schayer, Al Boasberg, and Sidney Lazurus) has Buster playing millionaire playboy Elmer J. Stuyvesant, a character similar to his roles in The Saphead, The Navigator, and Battling Butler.

It is the period of World War I.  While Elmer waits for Mary (Sally Eilers), the girl he has been trying unsuccessfully to impress, outside the store where she works, his chauffeur, stirred by a recruiter's speech about fighting the enemy, abandons Elmer and his manservant Gustave (Arnold Korff).  In need of a new chauffeur, Elmer unintentionally enlists in the army by mistaking a nearby recruiting station for an employment agency.

The film becomes a typical military comedy, with scenes in boot camp, complete with a belligerent drill sergeant (Ed Brophy), and in the trenches.  Military life is made tolerable for Elmer by the presence of the ukulele-strumming recruit Nescopeck (Cliff Edwards) and Mary, who has joined the army's entertainment division.  "Over There" in France, Elmer endures life in a trench for a short time before the war is over.

The film ends with Elmer and Mary as husband and wife, with Nescopeck and Elmer's other army friends as business partners in the manufacture of gold-plated ukuleles.

Cliff "Ukulele Ike" Edwards, a character actor famous for his trademark instrument, was responsible for the ukulele and the film's delightful musical interlude in which Buster, Edwards, and director Ed Sedgwick (who appears in the film as Guggleheimer, the camp cook) scat sing while aboard ship bound for France.  Edwards appeared with Buster in his next two films, and they became good friends, both delighting in singing old vaudeville songs and playing the ukulele.

The comic highlight of Doughboys is the stage revue performed for the entertainment of the troops in which Buster's character, dressed as a woman, is thrown around the stage as the female partner to an Apache dancer.  For this scene, Buster drew on his own wartime experience, as he had put on similar shows for the troops in France while waiting to come home.