In a video message posted to Biden's YouTube channel, Obama said the coronavirus emergency has shown the need for Biden as president, saying he has the temperament to govern a country in crisis.
"The kind of leadership that's guided by knowledge and experience; honesty and humility; empathy and grace -- that kind of leadership doesn't just belong in our state capitols and mayors offices. It belongs in the White House," he said. "That's why I'm so proud to endorse Joe Biden for president of then United States.
"I believe Joe has all the qualities we need in a president right now."
Biden, who served as Obama's vice president for his entire 8-year presidency, ran against Obama for the Democratic nomination in 2008. The 44th president said choosing Biden as his running mate was "one of the best decisions" he's ever made.
"And he became a close friend."
Obama said Biden would be ready on day one to take the reins of the federal government.
"He's someone whose own life has taught him how to persevere, how to bounce back when you've been knocked down," he said. "When Joe talks with parents who've lost their jobs, we hear the son of a man who once knew the pain of having to tell his children that he'd lost his."
Obama also touted Biden's experience when his administration organized against the H1N1 and Ebola epidemics and worked on other key issues like climate change.
"Joe was there as we rebuilt from the Great Recession and rescued the American auto industry," he said. "He was the one asking what every policy would do for the middle class and everyone striving to get into the middle class. That's why I asked him to implement the Recovery Act, which saved millions of jobs and got people back on their feet -- because Joe gets stuff done."
Obama stayed out of the Democratic race during the primary race when a number of candidates vied for the nomination. Vermont Sen. Bernie Sanders, Biden's last remaining competitor for the Democratic nomination, dropped out of the race last week and endorsed Biden on Monday.