Mr Sarkozy announced the major policy shift last week
The French parliament has backed President Nicolas Sarkozy's decision to take France fully back into Nato, rejecting a no-confidence motion.
Opposition critics and some among Mr Sarkozy's UMP party say the move will weaken French independence from the US.
But France's national assembly voted by 329 votes to 238 in favour of Mr Sarkozy's government.
The policy reverses a 1966 decision by the late President Charles de Gaulle to pull out of Nato's military command.
France is already among the top five contributors to Nato operations and currently has some 3,000 troops in Afghanistan, where it has suffered significant losses.
The outcome of the vote was never in doubt, the BBC's Alasdair Sandford reports from Paris.
The fact that this was a vote of confidence in the government ensured that dissenting voices within its ranks came on board in the end, our correspondent adds.
Conservative Prime Minister Francois Fillon proposed the no-confidence motion two weeks ago amid heavy opposition to boosting ties with Nato.
No fewer than four former French prime ministers came out against the move.
One of them, senior Socialist Laurent Fabius, questioned whether in 2003 France would have taken a lead in opposing the invasion of Iraq, had it been a full Nato player.
But Prime Minister Fillon told the national assembly in a pre-debate session that the decision to re-join was "simply an adjustment" rather than a break from the past.
He rejected criticism that Paris would be forced to bow to US interests, saying France was always an ally to the United States, but never subordinate.
President Sarkozy formally announced in a speech last Thursday that he wanted France to rejoin Nato's military command.
The move reversed a decades-old decision by President de Gaulle to pull France out of the Nato command and evict the alliance's headquarters from French soil to affirm France's independence and its rise as a nuclear power in the Cold War world.
Mr Sarkozy said there was no sense in France - a founder member of Nato - having no say in the organisation's decisions on military strategy.
The return to the military command is now expected to become official at Nato's 60th anniversary summit that will be jointly hosted by France and Germany in Strasbourg next month.