Hernández began his career in 2006, playing for Mexican club Guadalajara. In July 2010, he became the first Mexican player to join Manchester United, scoring 20 goals and winning the Premier League in his debut season, as well as playing in the final of the UEFA Champions League. After falling out of favour under managers David Moyes and Louis van Gaal, he spent the 2014–15 season on loan at Real Madrid. In August 2015, Hernández signed for Bundesliga club Bayer Leverkusen. After two seasons in Germany, Hernández returned to the Premier League and joined West Ham United. His minutes-per-goal ratio is among the most prolific in the history of the Premier League. Having garnered over 60 appearances for West Ham, Hernández returned to Spain with Sevilla in September 2019, only to depart four months later to join LA Galaxy.