This was the Massachusetts senator's first appearance in Washington since he was diagnosed with a cancerous brain tumour in May.
To cheers and applause, Senator Kennedy made a surprise appearance on the floor of the senate to vote on the bill he had helped fashion.
He was accompanied into the senate chamber by Senators Barack Obama and John Kerry.
He delivered his vote with a loud 'aye' and gave a thumbs up to the gallery.
Afterwards, accompanied by his wife Victoria and son Patrick, Mr Kennedy said he hoped to be able to return to Washington soon.
