Rooney appeared set to leave Old Trafford last summer after falling out with Sir Alex Ferguson, but has been in improved form under Moyes this season and ended the speculation over his future when he signed a lucrative new contract to keep him at the club until the summer of 2019 in February.
The 28-year-old is now just 38 goals shy of Sir Bobby Charlton's all-time scoring record, but his manager is adamant the striker's feats have already established him in the pantheon of greats.
"If you are third top scorer of a club like Manchester United you already are a legend," Moyes told reporters. "As long as he doesn't pick up any serious injuries he has a real good chance of breaking Denis Law's and Sir Bobby Charlton's records and that would be some feat.
"His form throughout the season has been very good and his goal against West Ham capped it all off. He showed what he is about and he has a big energy back again.
"Everyone who knew Wayne Rooney in his early days would say one of the biggest things about him was that he had big energy and a big heart and if you get Wayne playing like that then the rest of his football takes care of itself."