The singer is joined in his new group by former bandmates Gem Archer, Andy Bell and Chris Sharrock and admits they agreed to work together last August after guitarist Noel Gallagher quit the group following a row with his singer brother.
When asked how Beady Eye formed, Liam said: "It was that night. We all went back to the hotel, got on the p**s and it was like, 'Alright, lets f***ing do this.' I might have apologised to the lads, I might not have, I can't remember.
"We just got on with it. Because we knew right away that was definitely it. We knew it was done."
Gem added to NME magazine: "It was a long night. But I'd gotten to the point where I couldn't even think about playing with anyone else anyway. It wasn't so much about carrying on, we just drew a line and started something new. It took about a day."
Noel was the main songwriter for Oasis, but Liam insists he never had any doubts that he could be successful without his brother, and reckons the group now have more freedom.
He added: "Did I have doubts about if I would be able to do it without Noel? Never. Not at all.
"I can actually do more without him. It feels different to Oasis, it feels we can do thinks we couldn't have in Oasis. I don't know what exactly but I definitely feel a lot freer.
"Oasis was so f***ing set in stone. I was gutted at the time we split up, but that's life innit? S**t happens, you move on."