Mr Xi received a unanimous 2,952 votes on Friday from the National People's Congress, whose members are appointed by the ruling Communist Party.
Mr Xi, 69, who took power in 2012, began a third five-year term as party general secretary in October, breaking with a tradition under which Chinese leaders handed over power once a decade. A two-term limit on the figurehead presidency was deleted from the Chinese constitution earlier.
Mr Xi and those awarded other posts were believed to have run unopposed.
Under China's election process, delegates to the congress placed four ballots into boxes placed around the vast auditorium of the Great Hall of the People.
Mr Xi was also unanimously named commander of the two million-member People's Liberation Army.
In other voting, the party's third-ranking official Zhao Leji was named head of the National People's Congress. The vast majority of the body's legislative work is headed by its Standing Committee, which meets all year round.
Mr Zhao, 67, won Mr Xi’s trust as head of the party’s anti-corruption watchdog, the Central Commission for Discipline Inspection, pursuing an anti-graft campaign.
A former Shanghai party boss and member of the last Politburo Standing Committee, Han Zheng, was named to the largely ceremonial post of state vice president.
Mr Xi, Mr Zhao and Mr Han then took the oath of office with one hand on a copy of the Chinese constitution.
President Sheikh Mohamed congratulated Mr Xi on his re-election.
"Congratulations to my friend President Xi Jinping on his re-election as President of the People’s Republic of China," Sheikh Mohamed said on Twitter.
"We look forward to enhancing our comprehensive strategic partnership and we wish China and its people continued development and prosperity."