Abd-Rabbu Mansour Hadi took the constitutional oath as Yemen's new president on Saturday after winning a single candidate vote that ended Ali Abdullah Saleh's decades-long rule, al Jazzera television reported.
Hadi, who served as vide president undre Saleh, took power as part of a transfer deal brokered by the Gulf states and endorsed by Western countries.
"The election grants Yemenis the hope and it holds the parties and political forces the responsibility to overcome the past," Hadi said at a a ceremony in Sanaa attended by Saleh, who returned to the country on Friday after receiving treatment in the United States for injuries sustained in an assassination attempt last year.
"Power in Yemen is now based on popular legitimacy and no one can raise doubt about it."
Yemen's electoral officials said 65 per cent of eligible voters took part in this week's ballot.
Hadi will be sworn in on Monday.
Just hours after the ceremony, a car bomb in the southern city of Mukalla killed 26 elite republican guards, the al Arabiya news network reported.
No group has so far claimed responsibility for the attack.