Mass lynching will be outlawed for the first time under the amendment, which now only requires the president's approval before it becomes enshrined in law.
Organisations supporting believers under pressure for their faith have previously warned that false accusations of blasphemy - often used to settle personal scores - have prompted mob violence against Christians in Pakistan.
Samuel Pyara, president of the Bright Future Society, which raises awareness of Christian persecution, was quoted by AsiaNews.it as saying: "These measures were crucial to save our country.
"Mob justice has become a part of people's mind-set. There was a great need to make it a punishable offence and we appreciate the government's action."
Meanwhile, maximum jail sentences for inciting sectarian violence and ethnic hatred would be increased under the bill, from one year to three years.
The bill has been criticised by Pakistanis who support the country's blasphemy laws, which have been used to imprison Christians such as Asia Bibi.
The bill's statement of objectives claims "terrorism, sectarianism and extremism have gripped the entire country and these acts have become the order of the day."