Herrera was the subject of a £24 million offer from Manchester United in August 2013, but the bid was rejected by Athletic Bilbao.

A year later, Manchester United tried to sign him again.

On 26 June 2014, Athletic Bilbao announced on their official website that they had rejected a €36 million (£28.85 million) bid from Manchester United for Herrera.

Athletic Bilbao later confirmed that Herrera had activated his buyout clause, allowing United to sign him.

He made his Manchester United debut on 23 July 2014 in the first match of the club's pre-season tour of the United States, playing the full 90 minutes and making three assists in the 7–0 win over LA Galaxy.

Besides his passionate defense of the United badge, Herrera has won numerous man of the match awards and scored vital goals as he continues to underline his importance in the United side under Jose Mourinho.