The 29-year-old, who's contract at Old Trafford expires at the end of the season, has reportedly told French Ligue 1 champions Paris Saint-Germain he will join them ahead of the 2019-20 campaign.
United paid Spanish La Liga club Athletic Bilbao £29 million for Herrera in 2014 and despite on-going talks to extend his stay at Old Trafford, the two parties have reportedly failed to agree on terms.
In an interview with Diario ABC, Herrera admitted: "As it is right now, Manchester and I are not thinking alike."
The Spanish midfielder has scored 20 goals in 187 appearances for the Red Devils in his five years at the club, playing an integral role in the club's Carabao Cup and Europa League success under Jose Mourinho.
Herrera has featured 26 times across all competitions for United this season, but wasn't part of the squad that lost 1-0 to Barcelona in the UEFA Champions League on Wednesday.