The two Noble Peace Laureates greeted each other as Obama entered the ball room of a hotel here to deliver remarks at the high-profile National Prayer Breakfast, attended by around 3,000 US and international leaders.
The Dalai Lama, 79, was seated in the front row across Obama, who nodded and smiled at the Tibetan leader.
At the top of his remarks, the US President welcomed the very presence of the lama, whom Beijing accuses of being a separatist, seeking to split Tibet from the rest of China and of fomenting unrest in the remotely-located strategic region.
"I've been pleased to welcome him to the White House... on many occasions, and we're grateful he's able to join us here today," Obama said amid another round of applause.
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Obama and the Dalai Lama have held closed-door meetings three times at the White House so far but today's meeting was their public encounter.
"There aren't that many occasions that bring his Holiness under the same roof as NASCAR (National Association for Stock Car Auto Racing). This may be the first... But God works in mysterious ways," Obama said amid laughter from the audience.
There was applause as organisers recognised among the audience the 14th Dalai Lama, who fled Tibet in 1959 after a failed uprising against Chinese rule in his Himalayan homeland and has lived in exile in India ever since.
China had warned against the joint appearance by the two leaders that could affect ties, saying the American side must deal properly with relevant issues in "keeping with the overall interests of bilateral relations".