The 22-year-old announced in 2006 that he was taking a break from acting to pursue his passion for cars, saying he would return to work after two years.
But the ex-Malcolm in the Middle star has now put his West Hollywood home on the market for and plans to move to Arizona permanently.
A source told OK!, "He's moving to Scottsdale. He's decided to focus his energy on racing and feels that he doesn't need a home in Hollywood anymore."
Talking about leaving showbiz, Muniz said, "I really wouldn't mind if I never acted again. Racing is definitely my passion, this is my career now and what I definitely want to do for the rest of my life."