The royal newlyweds, fresh from their honeymoon in the Seychelles, greeted the Obamas in the grand 1844 room of Buckingham Palace after making a special trip to London to see the Obamas.
It was the first time Catherine had undertaken a role as a member of the royal family since her wedding on April 29.
A Clarence House spokeswoman said the couples spent around 20 minutes together, chatting informally.
No television cameras or reporters were allowed in the room for the meeting, but a photograph released of the meeting showed Michelle Obama chatting to Catherine while the prince was deep in conversation with the president.
Catherine, now officially known as the Duchess of Cambridge, was wearing a coffee-coloured dress while the First Lady wore a floral green dress with a bright pink bolero.