The vote was witnessed by journalists inside central Beijing's Great Hall of the People.
The legislature is packed with delegates loyal to the ruling Communist Party meaning Xi's re-election was never in doubt. On Sunday parliament voted to amend the constitution to remove
presidential term limits, meaning Xi can stay indefinitely.
Former top graft-buster Wang Qishan, a key ally of President Xi Jinping, was also chosen as vice president on Saturday, a widely-expected move that nonetheless breaks with convention and
underlines Xi's dominant authority.
Wang bowed twice and then walked over to Xi to shake his hand after the vote was announced inside Beijing's Great Hall of the People. Only one person voted against Wang out of the 2,970 votes cast.
Known as "the firefighter" for his central role in tackling issues like corruption and domestic financial problems over the years, Wang also has experience dealing with the United States in his former role as a vice premier who led annual economic talks with Washington.
He was a major player in Xi's battle against corruption, with dozens of senior officials jailed during his tenure as the top graft-fighter, including the fearsome domestic security chief Zhou Yongkang, now serving life in jail.
Wang's appointment has the potential to reshape what has traditionally been a ceremonial role.
China's relationship with the United States is likely to be a key part of his remit, according to diplomats and sources with ties to the leadership.