The former Saturday Night Live performer was unimpressed when the Baby hitmaker hosted an episode of the comedy sketch show because he arrived on set with a huge entourage.
Bill told Howard Stern on Sirius XM: "Justin Bieber showed up with like 20 guys. He had a guy holding a slice of pizza. A guy holding a Diet Coke. You're trying to fight through all these people to get dressed."
While Bill hated working with Bieber, he praised Justin Timberlake for his down to earth attitude.
Speaking about the Mirrors singer, he said: "He's great. Also, the guy doesn't show up with anybody. Timberlake, it was just him. He's a real class act, that guy."
Justin won rave reviews for his fifth stint as SNL host in March, which included cameos from Steve Martin, Chevy Chase, Dan Aykroyd, and Martin Short, and the episode logged its best ratings for over a year with 8.4 million viewers tuning in.
He is reportedly being considered to host next year's Academy Awards after impressing producers with his performance on the comedy sketch show.
A source said: "The Oscar honchos are in discussions with Mr. SexyBack already.
Getting Justin to host would now be a huge coup for the Oscars. He'd been considered before, but they always thought he was too young and not seasoned enough.
"Now, he's the frontrunner for the job after showing he knows how to sing, dance, host, and improvise on the spot."
- Bang! Showbiz