The 2021 USL League One season was the third season of USL League One. The regular season began on April 10 and ended on October 30, 2021. The playoffs was held from November 6 to 20, 2021.
North Carolina FC joined the league for this season, after leaving the USL Championship in what the team called a "strategic move" to enhance its youth development pathway.
Greenville Triumph SC were the defending champions on both regular season and playoffs. Union Omaha took both titles to won their first League One regular season and championship titles.
The 2021 USL League One Playoffs (branded as the 2021 USL League One Playoffs presented by TwinSpires for sponsorship reasons) was the post-season championship of the USL League One season.
Championship Game MVP: DamiÃÂ Viader (Union Omaha)
Ranked from highest to lowest average attendance.
|note=*Fort Lauderdale CF and Toronto FC II had all their matches behind closed doors. Forward Madison FC New England Revolution II and North Carolina FC Had 1 game not reported.
(H) â Home team<br>(A) â Away team