Yet the Mexican has admitted that when he was first approached by the club, he thought it was a joke and couldn't believe what has happening to him
"I had never heard of Jim Lawlor [United's head scout], I didn't know who he was," he told The Guardian.
"I didn't believe it. In Mexico, the agents put the badges of the clubs on their cards. I was thinking, 'ok, another one of them, hey?' I turned to my father and said 'Don't joke with me.' But then I saw he was crying. That was the moment I realized it was really true. It was really Manchester United."
Yet Hernandez has thrived at Old Trafford, surprising not just himself but also his manager Sir Alex Ferguson, who has admitted he didn't expect the youngster to play such a key role in his first season.
"The idea was he would spend his first year getting to understand United, build up his body strength, get used to England," Ferguson has said.
And ahead of the Champions League final, Hernandez says all of Mexico will be supporting him and reveals Mexico's friendly match with Ecuador has even been put back by two hours so it doesn't clash with the Champions League final.
"They are showing it [the Champions League final] live on television," Hernandez added.
"I read the newspapers back home and they are all supporting me and looking forward to the final. They have even changed the time of an international friendly so it doesn't clash."Yet despite his heroics this season, Hernandez also revealed that he almost quit the game two years ago.
"I wasn't getting the minutes I wanted, the coach wasn't playing me – I don't know why – and I was frustrated," said the Mexican.
"My confidence started to drop. It reached the point where I was no longer enjoying football. I went to my family and asked whether I should carry on.
"They told me I had devoted a lot of time to trying to make my dream come true and not to give it up. They said to keep fighting, keep focused and the most important thing was to keep enjoying the game because people all over the world want to be football players."
Watch the UEFA Champions League Final Barcelona vs. Manchester United this Saturday 5/28 at 2 p.m. ET on FOX! Click here for more.