The Portugal midfielder finished the season with eight goals and 20 assists in 37 league appearances, equalling the all-time Premier League single-season assists record held by Thierry Henry and Kevin De Bruyne.
He reached 20 with his assist for Bryan Mbeumo in a 3-2 win over Nottingham Forest last weekend, and can break the record outright when United visit Brighton & Hove Albion on Sunday in their season finale.
Fernandes created 132 chances in the league this season — 43 more than the next best, Liverpool's Dominic Szoboszlai.
The winner is decided by combining public votes with those from a panel of football experts. He saw off a shortlist that included Arsenal's David Raya, Gabriel and Declan Rice, Manchester City's Erling Haaland and Antoine Semenyo, Brentford's Igor Thiago and Nottingham Forest's Morgan Gibbs-White.
Fernandes is the first Manchester United player to win the award since Nemanja Vidić in the 2010-11 season.
The 31-year-old has been United's most consistent player across a season that began in crisis, with the club sitting in the relegation zone in January before Michael Carrick's arrival turned their campaign around completely. Fernandes contributed to 28 league goals in total and his leadership was cited repeatedly by Carrick as central to the turnaround that ultimately delivered a third-place finish and a return to the Champions League.
He has now won the FWA award and the Premier League's own honour in the same season — a double achieved by only a handful of players in the award's history.
One more assist against Brighton and the record is his alone.