The 17-year-old is the first Red to scoop the award after taking his goal tally to 30 in all competitions for the club in 2018/19.
Despite being the youngest of the five-man shortlist for the trophy, Mason came out on top after consideration from the panel, following his exploits throughout the month for Ricky Sbragia's side.
The centre-forward set up Nishan Burkart's effort in the 1-1 draw with West Brom on his maiden appearance at Old Trafford, crossing superbly from the right, and followed it up with a superb display at Newcastle United's St James' Park.
He again assisted the opening goal for Burkart and also converted a wonderful free-kick during a 5-0 success for the Reds.