"You know, as President, you make a lot of important decisions. Probably the most important decision is who is going to be your partner during the course of your presidency," President Obama said at an inaugural reception on Sunday.
"There have been some decisions I got right, some maybe folks might question. But one decision I know was absolutely correct, absolutely spot on, was my choice of Vice President. I could not have a better partner than Joe Biden," he said.
"Joe Biden couldn't have a better partner than Dr Jill Biden. We love these folks. Give them a round of applause," he added.
Earlier in the day, Obama was formally sworn in for his second term.
After the ceremonial swearing-in on Monday, Obama would deliver an address to the nation in front of hundreds of thousands of people at the National Mall facing the US Capitol.
"I'm delivering another speech tomorrow so tonight I'm going to be pretty brief, because there are a limited amount of good lines and you don't want to use them all up tonight. My main purpose tonight is just to say thank you," Obama said.
"Tomorrow, hundreds of thousands will join us in the National Mall. And what the inauguration reminds us of is the role we have as fellow citizens in promoting a common good even as we carry out our individual responsibilities -- the sense that there's something larger than ourselves that gives shape and meaning to our lives," he said.
Noting that the theme of this year's inauguration is "Our people and our future", Obama said throughout his career, what has always given him energy and inspiration and hope, what has allowed him to stand up when he has been knocked down, are folks like them -- the decency, the goodness, the resilience, the neighbourliness, the patriotism, the sense of duty, the sense of responsibility of the American people.
"You have inspired me throughout. So whenever I think about the challenges that Joe and I and Jill and Michelle face, we know that we stand amongst friends and colleagues and fellow citizens, and that the work is not just ours, that we are working together," he said.
First Lady Michelle Obama also spoke on the occasion.
"Let's remember that this inauguration is about more than all of the events that we will all enjoy this weekend. It's about more than swearing in a President. It's about more than we accomplish together over the next four years. It's also about the opportunities we have to make a real difference in people's lives," she said.
"I mean, the truth is it's about our opportunity to continue to lift up our families, to help more of our children achieve their dreams, and to put our country on a solid foundation not just for these next few years, but for generations to come," she said.
"So tonight, let us re-dedicate ourselves to that work. Let us keep building on the progress that we've made. And let's keep working and fighting and pushing forward to make the real changes that's happened. That is what this man, my husband, has been doing for these last four years," she said amidst applause.
"Let me tell you, it has just been a true thrill to watch this handsome, charming individual grow into the man and the President that he is. We have seen him every single day -- his integrity, his character, his sense of humour , his compassion, his courage," Michelle said.
"And no matter what the obstacles, we have seen him be so steady facing the challenges that lie ahead and, as always, held true to one unwavering belief -- and that is that we love this country, and we can all work together to change it," she added.
Biden said he has been especially honoured to serve as Barack Obama's Vice President.
"This man has already done an absolutely remarkable job: Historic health care reform, two Supreme Court appointees --Justice Sonya Sotomayor and Elaine Kagan -- ending the war in Iraq and about to end the war in Afghanistan -- and stating forthrightly his support for marriage equality. I want you to know something else about this guy Barack Obama -- he's just getting started. He's just getting started," Biden said.
"In the weeks and months ahead, we're going to reduce gun violence here in America. We're going to pass comprehensive immigration reform. And we're going to put this nation's economy on a sustainable path to the future," Biden asserted.