"Now I did not know this, but I was told that...it turns out that you and Bieber didn't have a friendship," DeGeneres asked the "Neighbors" actor.
"We had a beef," Rogen confirmed. "It's not really a beef, i just called him some really mean things on social media for no real reason."
"And I'd only met him very briefly...it was really just something I can’t tell you why I did it," Rogen continued. "And then it really hurt his feelings, as it should have. And a lot of people got very mad at me."
Luckily, the "I'll Show You" singer has been appearing on "Ellen" all week to promote his upcoming album, "Purpose," so Bieber and Rogen were able to finally bury the hatchet and let bygones be bygones.
"I finally saw him today in the hallway of your show and I guess we made up, which is fantastic,” Rogen said.
Bieber tweeted a video of their encounter, with Bieber's hit single "Sorry" playing in the background.
"Less than 48 hours to go and finally made up with @Sethrogen to celebrate #PURPOSE lol," Bieber wrote.
"Purpose" comes out tomorrow, Nov. 13, and his "Purpose World Tour" will kick off next March.