Burnley took the lead simply before half-time once Chris Wood spun off Harry Maguire to meet ben Mee’s knockdown and smash into the top corner from the sting of the six-yard box.
Jay Rodriguez doubled the Clarets’ advantage once he contend a one-two with Wood before firing into the top corner of David de Gea’s close to post with a venomous strike from the left-hand corner of the penalty space.
It was the third season during a row Burnley had gone 2-0 up at old Trafford, but for the first time they persevered for all 3 points.
United, who were without the injured Marcus Rashford, were lacklustre for large periods and barely vulnerable Nick Pope within the Burnley goal.
They were booed off at half-time and regular and large parts of the ground emptied with 5 minutes left.
Ole Gunnar Solskjaer’s side stay six points behind Chelsea and off the top four, whereas Burnley climb to thirteenth, seven points beyond the relegation zone.