The third season of the television series Ally McBeal commenced airing in the United States on October 25, 1999, concluded on May 22, 2000, and consisted of 21 episodes.

On the 52nd Primetime Emmy Awards, the show won an Emmy in the category of Outstanding Sound Mixing for a Comedy Series or a Special for the season premiere episode Car Wash.[4] Kevin Fallon cited the sex scene from the episode Car Wash as one of "TV's 13 Dirtiest Sex Scenes" in a column for The Daily Beast.

Calista Flockhart as Ally McBeal, Greg Germann as Richard Fish, Peter MacNicol as John Cage, Jane Krakowski as Elaine Vassal, Lisa Nicole Carson as Renée Raddick, Gil Bellows as Billy Thomas, Courtney Thorne-Smith as Georgia Thomas, Vonda Shepard as herself, Portia de Rossi as Nelle Porter and Lucy Liu as Ling Woo all returned to the main cast.

[8] Various supporting characters from the previous seasons returned to reprise their recurring roles, including Dyan Cannon making her final appearances as Judge Jennifer "Whipper" Cone, Albert Hall as Judge Seymore Walsh, Jennifer Holliday as Lisa Knowles, Harrison Page as Reverend Mark Newman, Tracey Ullman as Dr. Tracy Clark, and Renée Elise Goldsberry, Vatrena King and Sy Smith as the backup singers for Vonda Shepard.

Farrah Fawcett portrays Robin Jones, a newspaper editor accused of sexual harassment.