Goals from Marouane Fellaini, Jesse Lingard and Antonio Valencia moved Manchester United to fifth in the Premier League table.
Manchester United opened the scoring in the 30th minute. Marouane Fellaini headed home a wonderful Ashley Young cross.
Middlesborough, who showed a lot of determination and fight in the opening half, caused Manchester United no problems going into the final third.
Jesse Lingard furthered Manchester United’s lead in the 64th minute, with the 24-year-old’s strike from 25-yards out floating into Victor Valdes’ net.
Rudy Gestede grabbed a consolation for Boro, with the January signing striking in from a Chris Smalling defensive error.
However, before Middlesborough could try and get an equaliser in stoppage time, Manchester United right-back Antonio Valencia tapped in from former Manchester United goalkeeper Victor Valdes’ mistake.