The room erupted into loud applause when the result of the vote was passed with 2958 in support. Two voted against, while three abstained and one ballot paper was spoiled, signifying almost total loyalty to Xi's vision for strongman rule.
At least two thirds of delegates were required to vote in favour of the constitutional changes to allow Xi to rule beyond the end of his second term in 2023.
Observers now believe the Chinese President is almost untouchable.
Andrew Nathan, a China expert at the University of Columbia, said Xi has "locked up every possible source of power in the tripartite party, state, and military apparatus".
He added: "I have no doubt, human nature being what it is, that there are many party elites who are jealous and disapproving of him, or who hate him, partly due to the anti-corruption campaign and partly due simply to his monopolising power in this way.
"But they have been isolated, cowed, and silenced. Although it is hazardous to make predictions about China, I can see no sign of a brewing power struggle. Xi seems secure."
The ruling Communist Party says the move to scrap presidential limits has received widespread support from officials and ordinary people. China's tightly controlled media have presented it as a routine matter.
But the country's huge army of internet censors has been forced to mobilise to confront criticism on social media.
Authorities have also moved to silence critics who have expressed concern about a return to one-man rule in a nation that now ranks among the most powerful on earth.
Professor Roderick MacFarquhar, a former China correspondent at the Daily Telegraph and a current China expert at Harvard University, said Xi's power grab still relied on the support of China's People's Liberation Army (PLA) in the long term.
"One bad adventure could lead to Xi being ousted," MacFarquhar said. "The one group that Xi has to keep on side is the military."
The parliament also backed inserting Xi's political theory into the constitution, a feat no other leader since Mao had managed while in office.
The party gave Xi the title of "core" leader in 2016, a significant strengthening of his position at the time.
An emerging "cult of personality" has seen him being bestowed with a range of adulatory titles, and one local official recently likened him to a living Buddhist deity.
Name game: Xi's seven titles
1) General Secretary of the Communist Party: The most important title
2) President: Not usually used in China
3) Central Military Commission Chairman: Signals power over generals
4) Xi Dada: Means 'Big Daddy' and boosts his 'man of the people' credentials
5) Core leader: Signals total domination over the party
6) Living Buddhist diety: Someone on the path to becoming a Buddha
7) Lingxiu (Leader): Term last bestowed on Chairman Mao, re-emerged after last year's Party Congress
