The year 2021 was the 29th year in the history of the Ultimate Fighting Championship (UFC), a mixed martial arts promotion based in the United States.

Starting in 2019, the UFC created year-end awards with "UFC Honors President's Choice Awards" for categories "Performance of the Year" and "Fight of the Year" being chosen by UFC CEO Dana White. The other "UFC Honors Fan Choice Awards" are for categories "Knockout of the Year", "Submission of the Year", "Event of the Year", "Comeback of the Year" and, from 2020, "Debut of the Year" in which fans are able to vote for the winner on social media.

Winners receive a trophy commemorating their achievement along with a set of tires from sponsor Toyo Tires.

These fighters have either been released from their UFC contracts, announced their retirement or joined other promotions:

The following fighters fought their first UFC fight in 2021:

The list below is based on fighters suspended either by (1) United States Anti-Doping Agency (USADA) or World Anti-Doping Agency (WADA) for violation of taking prohibited substances or non-analytical incidents, (2) by local commissions on misconduct during the fights or at event venues, or (3) by the UFC for reasons also stated below.

The following The Ultimate Fighter seasons are scheduled for broadcast in 2021: