The topic came up when the pop-star sat down with the talk show host for an exclusive one-on-one interview.
Winfrey offered up advice to the star, explaining why she thought 25 was too young for marriage.
"Your whole 20's is about discovering who you really are and you owe that to yourself particularly because you are in the business that you're in and it's not a lot of self-discover time because so much is already defined for you. So, you are entitled to your own opinion but rethink it," explained Winfrey.
Bieber agreed to rethink his plans.
The 18-year-old also revealed how hard it is to build trustworthy relationships while being under the spotlight: "It's hard, I try to keep the people that have been around me since the beginning, you know, close to me. I really don't have a lot of friends, I have like three close friends that I'll fly out to see me or I chat with or call. But, I mean, that's really the truth."
When asked if life in the public eye ever makes him lonely or depressed, Bieber answered by saying, "yeah, sometimes."
"Not like super, super, super depressed but like I get days where like I am just down and, you know, gloomy," he said.
Saying simply being "human" was the reason.
"Some days you just feel what you've gone through - I don't know if you get what I'm saying? Like you just, you have pain in your heart because maybe you haven't dealt with that. Sometimes that just puts weight on you and you just have a bad day and you don't even know why, you're just depressed because you don't deal with what you're going through," he added.
Winfrey lightened things up by asking about his infamous hair and the thought process behind cutting his mane.
"I loved my long hair, but I was getting tired of it, I felt like everyone else got that hair style and then I wanted to change it up a little bit," Beiber told Winfrey.
The entire interview will air on the Oprah Winfrey Network (OWN) on Sunday, November 25 at 9pm EST (0200 GMT November 26).