The US President had previously stated his opposition to the idea, but has changed his stance after talking to staff members, gay and lesbian service members and his family.
"When I think about those soldiers or airmen or marines or sailors who are out there fighting on my behalf and yet feel constrained, even now that Don't Ask Don't Tell is gone... at a certain point I've just concluded that for me personally it is important for me to go ahead and affirm that I think same sex couples should be able to get married," he told Robin Roberts on ABC News.
However, the 50-year-old admitted that this is his personal position and he still supports states deciding on same-sex marriage themselves.
He also revealed that First Lady Michelle Obama was part of his change of mindset, stating that "she feels the same way [he does]".
"We are both practising Christians and obviously this position may be considered to put us at odds with the views of others but, you know, when we think about our faith, the thing at root that we think about is, not only Christ sacrificing himself on our behalf, but it's also the Golden Rule, you know, treat others the way you would want to be treated," he continued.
"And I think that's what we try to impart to our kids and that's what motivates me as President and I figure the most consistent I can be in being true to those precepts, the better I'll be as a dad and a husband and hopefully the better I'll be as President."
He recently hosted the White House Correspondents' Association annual dinner attended by numerous celebrities including Charlize Theron, Lindsay Lohan, Zooey Deschanel, Viola Davis and Kim Kardashian.
The President's interview will air on Good Morning America on Thursday, May 10.
Watch Jimmy Kimmel at the White House Correspondents Dinner below: