The actor, who then shot to even bigger fame in Twilight, played Cedric Diggory in Harry Potter And The Goblet of Fire.
An overrunning production schedule, it seems, stopped him from pursuing higher education.
“That [role], more than anything, changed my life,” he told Time Out.
“It’s the reason I didn’t go to university.”
He elaborated: “It went so far over schedule, I couldn’t go. It was supposed to be four months, but it ended up being ten or 11.
“I’d turn up to set every day but not work for weeks at a time [because he wasn’t needed for filming].
“I was 17 and I was the only person who wasn’t in school. I’d just hang about.’
The star is currently promoting his role in Good Time, which has picked up strong buzz.
The film currently has a rating of 90% on Rotten Tomatoes, and saw Pattinson nominated for Best Actor at the Gotham Independent Film Awards.
Jennifer Jason Leigh, Ben Safdie and Barkhad Abdi also star.
Good Time is out on Friday in the UK.