The Senate on Tuesday passed the crucial delimitation bill with 84 voting in favour of the motion and one against.
The 24th Constitutional Amendment Bill 2017 will allow the conduct of delimitation of constituencies on the basis of provisional census results. The National Assembly had already passed the bill last month.
The Senate was unable to vote on the bill on November 17 when it was first tabled in the Upper House as several legislators had remained absent from the session on that day, with only 58 of the 104 senators present.
The bill was again placed on the Senate's agenda on November 20. However, the absence of lawmakers had once again delayed voting on the bill. Leader of the House Raja Zafarul Haq had sought deferment for two days and the bill was placed on the Senate's agenda for November 22 but the House again failed to carry out a vote on it.
Under the terms of the amendment, while the number of NA seats will remain the same, Punjab will lose out on seats as its share in Pakistan's population has fallen to 52pc in 2017 from 56pc in 1998.
Balochistan and Khyber Pakhtunkhwa will gain the seats lost by Punjab, while Sindh's share will remain the same.