The 29-year-old has signed a five-year contract which will keep him at the club until June 2024. "I really wanted to join Paris and wear these colours," said Herrera, who has been capped twice by Spain.
"The club has a very beautiful story and I'm happy to be able to write new pages. Joining this club is an extraordinary feeling. I promise you three things -- work, professionalism and passion ".
Herrera joined United in 2014 from Athletic Bilbao and scored 20 goals in 189 appearances during his five-year stint at Old Trafford -- becoming a go-to player in big matches, especially under former manager José Mourinho.