The SGB Championship 2021 was the second tier division, called the SGB Championship, of the British speedway championship in 2021. Changes from the last edition of the Championship (held in 2019) were the addition of three teams and the loss of two teams. The 2019 Premiership club Poole Pirates, were the biggest profile club to join the league after dropping down from the highest league. Also the Kent Kings and Plymouth Gladiators both joined the league from the National Development League. Sheffield Tigers left the league to move up to the highest division and Somerset Rebels withdrew from the league altogether.