In addition, three existing teams made their IFL on-field debut after the 2020 season was cancelled because of the COVID-19 pandemic.
[3] As there were still many pandemic-related restrictions still in place during early 2021, the start of the season was delayed from February to April with the postseason to begin in August.
The top eight teams qualified for the postseason with the Massachusetts Pirates, playing their first season in the IFL, defeating the Arizona Rattlers in the United Bowl on September 12.
[7] The 2020 expansion Oakland Panthers,[8] as well as the Cedar Rapids River Kings, Quad City Steamwheelers, and the San Diego Strike Force withdrew from the season due to the effects of the pandemic.
[12] The season began on the weekend of April 23–24 with two games: the Bismarck Bucks at the Green Bay Blizzard and the Massachusetts Pirates at the Louisville Xtreme.