The Northern Ireland international linked up with United in pre-season after he was released by Leicester City at the end of his contract. Evans trained at Carrington and played in pre-season friendlies for the club.
But United have now tied the 35-year-old down to a contract and he will be available to feature for the first-team in competitive games this season, adding to his 198 first-team appearances in his first spell at the club, which yielded three Premier League titles and a Champions League crown.
Evans signs at a time when United are without Raphael Varane, who is set for around a month on the sidelines after picking up an injury in the win against Nottingham Forest last week, and he is delighted to be returning to the club where he made his breakthrough.
I am delighted to join Manchester United, a place which has always felt like home,” said Evans. “This club and the fans have shaped me as a player and as a person since I was 15 years old, and I am delighted to be back where it all began as part of this talented squad.
“Ive really enjoyed working under the manager and his coaching staff since the start of pre-season, and Im looking forward to helping this group achieve success together at this fantastic football club.
Evans will be a squad member under Erik ten Hag but has impressed the coaching staff this season both on and off the pitch, according to football director John Murtough.