The attendance of 18,524 against Sunderland at The Den was the highest since an FA Cup game against Chelsea in 1995.

Note: Flags indicate national team as has been defined under FIFA eligibility rules.

On June 8, Millwall announced their first two pre-season friendlies, against Dartford and Ipswich Town along with a training camp in Republic of Ireland.

[50] On 13 July, the club announced they would host Hammarby at The Den in a pre-season meeting.

[51] A mid-season friendly during the 2022 FIFA World Cup winter break against Brøndby was announced.