1000-1 outsider Miller beat Honda factory rival Marc Marquez by nearly two seconds after restarting the race in treacherous conditions when many of the sport’s stars retired – including Valentino Rossi in the lead.
Miller’s best result in MotoGP so far was 10th, most recently at Barcelona. Injuries have plagued his time in the top category, including a broken leg sustained in a motocross training accident earlier this year.
“I don’t know how to feel right now,” said Miller, who won in his 25th premier class start.
“A lot of people have badmouthed us and said this project wouldn’t work – but I just hope we’ve shown them otherwise and that we can ride bikes, that I’m not an idiot.
“Thanks to Honda for taking this risk. It is amazing. I can not speak.
“It was really nice to stay on the bike as I’ve been known to throw it off in similar positions,” he added. “It was really nice staying today and getting through the past year.
“In order not to miss a lot of a championship [in Moto3 in 2014] and then coming here was tough, a tough part of my career.
“Okay, we’re not expecting miracles after that, it was a win in rainy weather, it’s nice to have that under our belt.”