FIFA set the deadline for 2026 World Cup final squads at June 1, with official confirmation coming the following day. Teams submitted their 26-player rosters knowing that changes would be severely limited once the tournament approached. The regulations establish a clear framework for roster management during the competition.

Injury replacements remain the primary avenue for squad modifications, but only up to 24 hours before a team's opening match. England's Tino Livramento withdrew after a training injury, prompting Thomas Tuchel to call up Trevoh Chalobah from the standby list. Scotland faced a similar situation when Billy Gilmour picked up an injury during their friendly against Curacao, leading to teenager Tyler Fletcher receiving his first senior call-up.

Seven other nations including South Korea, Bosnia and Herzegovina, and Canada have also altered their initial selections due to fitness concerns. The goalkeeper position operates under different rules, allowing replacements at any point during the tournament if a serious injury occurs. Both England and Scotland ultimately named full 26-player squads featuring three goalkeepers each, meeting the minimum requirement of three goalkeepers in the final roster.