As part of a training camp in Hungary, the club arranged a behind-closed-doors friendly against III.

Source: [citation needed] Rotherham United's fixtures were announced on 24 June 2021.

[15] The Millers were drawn at home to Accrington Stanley in the first round.

[16][17] Rotherham were drawn into Northern Group E alongside Doncaster Rovers, Manchester City U21s and Scunthorpe United.

[18] The group stage match dates were confirmed on July 9.