The 2021–22 season was Millwall's 137th year in existence, 95th consecutive season in the Football League, and 45th in the second tier. The club competed in the Championship for the fifth consecutive season and finished ninth. Millwall had a chance of making the play-offs right down the last game day, but ultimately missed out by six points. The team also played in the FA Cup and League Cup, and were knocked out in the early rounds.