Sstrict security measures were seen in all over the constituency where police Pakistan Rangers and Pakistan Army kept alert for maintain smooth polling process.
More than 320,000 voters are taking part in the poll, which for the first time in Pakistan's history will be conducted using Biometric Voter Verification Machines in some the constituency's 220 polling stations, Dawn News reported.
A close contest is expected between Kulsoom and Rashid.
Maryam Nawaz says she is not concerned about the political impact of the new parties but about "the kind of resources they have. If they can't win this seat by a big margin - or could even lose - it is awesome".
The latest ruling comes days ahead of a by-election to fill Sharif's parliamentary seat in Lahore that is being contested by his wife Kalsum, who is being treated for throat cancer in London. "Will you stand with your judiciary or with the biggest thieves of this country?"
Some PML-N circles believe the political environment is not conducive for Sharif's return and hence, he has been advised to stay in London for some time.
The premier arrived in London on Saturday en route to NY to participate in the 72nd session of the United Nations General Assembly (UNGA) commencing from September 18.
The result of this by-election will provide some insight into what could happen in Pakistan's 2018 general election. Then he added mildly, "However, we will win".
"She is under medical treatment and will undergo another surgery after few days", Nawaz told reporters in London where he is now residing with his sons.
The PML-N leadership is waiting to see the outcome of the NA-120 by-elections. They filed for a review petition to Pakistan's Supreme Court, which was dismissed on Friday, 15 September, 2017. She said the people of Pakistan "know everything, and they have supported us throughout".
"You took the brunt of the attack against Nawaz Sharif", she said, while hailing people of the constituency.
The members of the Sharif family have been summoned by the accountability court on September 19 and Dar on September 20.