The former Germany captain retired from international football earlier this week after 24 goals and 121 caps.
All 20 top-flight clubs had to submit their 25-man squads to the Premier League by 16:00 BST on Thursday.
Under-21 players – like Marcus Rashford, Luke Shaw and Anthony Martial – are eligible over and above the limit of 25 players per squad.
Schweinsteiger, who signed a three-year contract in July 2015, has trained alone and with the under-23s since Mourinho took charge in the summer.
The former Bayern Munich star said he “will be ready if the team needs me” but Mourinho says Paul Pogba, Marouane Fellaini, Morgan Schneiderlin, Ander Herrera and Michael Carrick are above him in the pecking order.
“We have five players for two positions,” said the United boss, who took over from Louis van Gaal. “It’s very difficult that an opportunity will arrive.”