Pakistan is set to try terror suspects in military courts as part of plans to tackle insurgents after last month's school massacre in Peshawar.
Most parties backed the constitutional amendment in parliament's lower house, which needed a two-thirds majority.
It is the latest in a raft of anti-terror moves after the attack. Critics oppose handing the army more power and say suspects' rights are at risk.
The 16 December Taliban attack left 152 people dead, including 133 children.
On Monday, Pakistan Taliban leader Mullah Fazlullah released a video vowing more attacks on children.
Pakistani civil society activists shout slogans against Taliban during a peace rally in Lahore on January 5, 2015.
Many Pakistanis hope the attack marks a watershed in the country's war with militants
Analysis: M Ilyas Khan, Islamabad
It's only a matter of time before the military courts plan becomes law. The move is clearly in response to public demands for swift justice, and stems from a feeling that the judiciary has failed to convict militants. But have the reasons that led to the judicial failure been addressed?
Experts point out that the main failure of the system lies at the investigation stage. No legislation was ever attempted to enhance police powers to investigate terrorism-related offences. In scores of cases the police were forced to either release known militants they had arrested or just ignore their movements because they were thought to be allies of the security establishment.
Also, no witness protection programme was ever developed, and eyewitnesses hardly ever appeared in terror cases. Judges and prosecutors faced threats to their lives, too, making successful trials well nigh impossible even if evidence was available.
Civil activists say nothing has been done to fix any of these problems and they are yet to see conclusive proof that the state has actually decided to eliminate the non-state actors it is accused of nurturing. This is creating fears that the military courts may become an instrument of selective justice, and may further empower the military.
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The bill introducing military trials for insurgents will now pass to the upper house before being signed into law by the president later this week.
Local residents torch tyres and cloths as they block a street during a protest in Peshawar on December 31, 2014, against the Taliban militant attack on an army-run school.
Locals in Peshawar held protests against the Taliban attack
It received the votes of all 242 lawmakers present, 14 more than the two-thirds majority required. Members of two religious parties and the opposition PTI party of former cricketer Imran Khan abstained.
Prime Minister Nawaz Sharif said in late December that establishing military trials would help ensure "terrorists pay the price" for their "heinous acts".
The military and government have said the trials are a response to extraordinary circumstances and will only remain in place for two years.
Interior Minister Chaudhry Nisar Ali Khan said last week that they would have a limited mandate, and that ordinary civilians would not be pursued by them.
The leader of the opposition, Syed Khursheed Ahmed Shah, said in parliament on Tuesday that while he had not been in favour of military courts in the past, "the Pakistani public's safety is our priority and it is the government's responsibility to keep the masses safe in this country".
"The bitter pill of this new law is being swallowed for the security of Pakistan," the Dawn newspaper quoted him as saying.
In an editorial the newspaper said political leaders had abdicated their responsibilities.
Critics of the military courts oppose handing the army more powers in a country with a history of military coups.
They also fear the process will lead to innocent people being convicted and executed without independent scrutiny inside the courts.
In the wake of the Peshawar attack, Pakistan also lifted a moratorium on the use of the death penalty, meaning hundreds now face execution.
Human rights groups say this will not combat terrorism and will only perpetuate a cycle of violence.
The military has also stepped up its campaign against militants in the tribal areas in the north-west of the country.
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