The England Under-21 international will stay on loan with the Chairboys until the end of the season.
“I’m delighted to have signed someone of his quality,” Wycombe manager Gary Waddock told the club’s official website.
“Coming from a club like United and with the league experience he has gained, I’m sure that Tom will be a very good acquisition.
“Manchester United have been very helpful in letting Tom join us and I’m looking forward to working with him.”
