The PFL 4 mixed martial arts event for the 2021 season of the Professional Fighters League was held on June 10, 2021. This was the fourth regular season event of the tournament and included fights in the Featherweight and Lightweight divisions. Boxing champion and Olympic gold medalist Claressa Shields made her MMA debut in the main event against Brittney Elkin.

The PFL 1 mixed martial arts event for the 2021 season of the Professional Fighters League was held on April 23, 2021. This was the first regular season event of the tournament and included fights in the Featherweight and Lightweight divisions. The event was headlined by a lightweight clash between the former UFC and WEC Lightweight champion Anthony Pettis and the UFC veteran Clay Collard.