The 30-year-old reality star revealed the deception during his weekly podcast with Dr. Mike Dow on Thursday. Jenner and Conrad appeared to date on two seasons of The Hills, but he said the relationship was faked for television.
"Lauren Conrad and I never dated," Jenner admitted. "Lauren and I have always been just friends. We worked together on a show called The Hills where we had to pretend like we were dating, but we never dated."
The star says the faux romance extends to ex Kristen Cavallari as well.
"I dated Kristen when we were very young ... when she was on Laguna Beach and I was on a show called Princes of Malibu with Spencer Pratt," he shared. "We met at a party in Hollywood ... but during The Hills when we filmed, Kristen and I did not date, we were not hooking up."
The Hills debuted in 2006, and ran for six seasons on MTV. Jenner now occasionally appears on Keeping Up the Kardashians with father Bruce, stepmother Kris and the various Kardashian siblings.