The 23-year-old right-back has signed a contract that takes effect on January 1 and is valid until June 2029.
Lundkvist - who can also play central midfielder - will be the fourth blue-yellow United player. The club already has the international trio Fridolina Rolfö, Julia Zigiotti Olme and Anna Sandberg playing for the club.
"It feels very good to be here. Manchester United is a club with a fantastic history. You really feel how much they have grown in recent years and are now competing in one of the world's toughest leagues," says Hanna Lundkvist to the club's website.
Earlier in December, Lundkvist announced that she was leaving San Diego after two years in the United States. Before that, she played for Atlético Madrid in the Spanish league, where she joined as a 19-year-old from Hammarby in 2021.
Manchester United are currently fourth in the English Super League and have also qualified for the round of 16 in the Champions League.
