Marcus Rashford’s 15th Premier League goal of the season and 28th in all competitions for his club secured the win.
It took United back above Tottenham in the race to qualify for the Champions League, and was the response manager Erik ten Hag needed following Sunday’s defeat at Newcastle.
Brentford, who are chasing European qualification, lost for only the second time in 17 Premier League matches.
Scott McTominay and Antony went close before Rashford finished from close range, with a headed assist by Marcel Sabitzer, after the Bees failed to deal properly with a corner.
