When star Diana Golden (Betty Jane Rhodes) performs for a gathering of sailors, shy sailor Casey Kirby (William Holden) goes backstage to get her autograph for his sister. Casey is tricked into a publicity kiss with Golden for the cameras and when his buddy, Barney Waters (Eddie Bracken), reports back to their buddies on ship, the kiss instantly creates Casey's reputation as a notorious ladies' man. When Jake (Leif Erickson), a real "Don Juan," bets Barney that Casey will not be able to kiss "The Countess," a dance hall singer who is renowned for her aloofness, Barney bets his friend Spike's antique watch, and wagers spread shipwide.

Spike (Gil Lamb) threatens Barney with death unless he wins the wager, and so when they dock in San Francisco, Barney immediately takes Casey to The Countess's dance hall, Swingland, and engineers Casey into sitting with the disinterested singer. The Countess (Dorothy Lamour) pretends to take an interest in Casey when the manager tries to force an obnoxious patron on her, and Casey ends up walking her home. The Countess becomes charmed by Casey despite herself, and she invites him into the hillside apartment she shares with singer Bessie Dale (Betty Hutton).

Bessie returns the same night with Barney, and both couples pursue their flirtations until Barney mentions his wager to Bessie. Bessie interrupts Casey and The Countess just as they are about to kiss and tells The Countess about the bet. Both Barney and Casey are thrown out of the apartment, but Casey soon realizes that he is sincerely in love with The Countess and buys an engagement ring. Bessie meanwhile reveals to The Countess a plan she heard from Barney, in which Casey will propose to her in order to get a kiss.

When Casey does propose, the outraged Countess throws the ring out the window, but Casey explains his sincere intentions, and they retrieve the ring. That night during the show at Swingland, Casey tries to propose again while The Countess dances on a conga line. The club's bouncers think he is drunk and wrestle him to the floor, and a brawl ensues involving all the visiting sailors. Casey is dragged off unconscious as the shore patrol arrives and is later brought to trial as the initiator of the brawl.

He refuses to defend himself until The Countess strolls into the courtroom and adopts a hard-boiled attitude, pretending that she deliberately led Casey on to get the ring, and that the bouncers threw the first punch. Casey is acquitted and in the taxi on the way to the Navy dock, Casey and The Countess are married by a minister. At the dock, all the sailors witness Barney win his bet as Casey and The Countess finally kiss.

"The Fleet's In" marked Betty's feature film debut.

This film is partly based on the 1928 film of the same name, which starred Clara Bow, as well as a play by Kenyon Nicholson and Charles Robinson. Other Paramount films based on Kenyon Nicholson and Charles Robinson's play include "Lady Be Careful" (1936) starring Lew Ayres and Mary Carlisle and "Sailor Beware" (1952) starring Dean Martin and Jerry Lewis, which features a brief cameo appearance by Betty.

The largest indoor set ever built at Paramount at the time was a ballroom for "The Fleet's In", which featured Betty and 400 extras going through a three-day fight scene.

When Private Don Ridnour, an old schoolmate of Betty's from Lansing, Mich., asked her for a date, she not only gave him one but rented the Filmarte Theater and threw a party for his entire outfit, screening "The Fleet's In" for the first time.

Director/composer Victor Schertzinger died on October 26, 1941, three days before the end of the film's production. According to Hollywood Reporter news items, Ralph Murphy finished directing the film but declined screen credit "so that the film could stand as a monument to a fine musical talent."

A Hollywood Reporter news item reported that Bob Hope (in the Eddie Bracken role) and Bing Crosby (in the William Holden role) were originally slated to star in "The Fleet's In".

Paramount made prints of Betty's "Arthur Murray Taught Me Dacing In A Hurry" number for a distribution tie-up with the Arthur Murray Dance Studios.

From Erskine Johnson's column: "Since Betty Hutton introduced 'Arthur Murray Taught Me Dancing,' she has been invited to 20 different army camps to teach the boys how to rumba. They don't know that Betty is really taking rumba lessons herself from Murray."