Three days after mocking Trump as unfit to control the codes needed to launch nuclear weapons, Obama told his successor that he wanted him to succeed and would do everything he could to ensure a smooth transition.
Trump, who spent years pursuing Obama over false claims he is not a natural-born American and accused him of being the founder of ISIS on the campaign trail, called Obama a "very good man" and said he would seek his counsel in future.
The extraordinary meeting was a reflection of the swift and sudden change in the political mood between the frenzied last days of an election campaign and the reality of government and the transition of power between two administrations that follows.
"My No. 1 priority in the next two months is to try to facilitate a transition that ensures our President-elect is successful," Obama said.

Obama told Trump: "If you succeed, the country succeeds," as the two men sat in high-backed chairs in front of the fireplace in the Oval Office.
Trump thanked Obama for the meeting which he said had originally been scheduled for 10 minutes and went on for 90.
"Mr. President, it was a great honor being with you and I look forward to being with you many, many more times," Trump said, adding that he and Obama had spoken about some wonderful and difficult things and "some high-flying assets."
It was not immediately clear what he meant.
The President-elect also said he would seek "counsel" from Obama.
As the pool of reporters were led out, Trump told them several times that Obama was "a very good man."
It comes with many Americans, especially Democrats and liberals, still in disbelief and shock at Trump's victory over Hillary Clinton on Tuesday, after the most vicious and unconventional campaign in modern history.
The meeting, and Trump's stern demeanor, also underscored how the heavy burden of the presidency begins to settle on the shoulders of a President-elect. In Trump's case, that process will be especially challenging giving that he will be the first president elected with not political, diplomatic or military executive experience.
Republican National Committee chairman Reince Preibus, who is being mentioned as a possible chief of staff in Trump's White House, told CNN's Jake Tapper that Americans would appreciate Trump's demeanor in Washington.
"I hope that everyone has seen sort of this presidential Donald Trump that we knew all along was up to the task and I think is going to make us all proud," Preibus said.
Thursday evening, Trump tweeted about the meeting, writing, "A fantastic day in D.C. Met with President Obama for first time. Really good meeting, great chemistry. Melania liked Mrs. O a lot!"