The Gavin & Stacey star told the Evening Standard that he undertook 18 months of therapy following a period of hard partying, and would "recommend it" to anyone.
"It's just sitting talking to someone, but when you say things out loud you think more about how you've been behaving at certain times," said Corden.
"I was aware that perhaps I was becoming a bit of a d**k. Therapy is nice. I'd recommend it to anyone. It has been beneficial to me being happier and a better boyfriend and a better friend.
"I'm just grateful that I was able to sort of wake up in enough time."
Corden became engaged to partner Julia Carey in December, and recently welcomed his first child Max. He praised his fiancée in the interview, saying "She's the best thing that's happened to me.
"She's just really nice to me. The truth is, all that time I was going out, it was only ever to look for someone I could stay with."