Akihito used the occasion to reveal he had undergone heart surgery in February so that he would be able to attend a national memorial ceremony for the victims of the huge quake and tsunami.
"I expressed my wish to attend the ceremony ... so the surgery was carried out to meet this schedule," the emperor told reporters at pre-birthday news conference.
In a public address at the Imperial Palace in Tokyo, Akihito told the nation he was feeling fine and carrying out his official duties.
He also sent his best wishes to everyone who was affected by the disaster. "Our hearts will be with the afflicted people and I wish you all happiness," he said.