Sikandar Sultan Raja was sworn in on Monday as the new Chief Election Commissioner (CEC).
He was administered oath by the Chief Justice of Pakistan Gulzar Ahmed at a ceremony at the Supreme Court in Islamabad.
Raja was chosen to head the commission by a parliamentary committee comprising government and opposition members.
The seat had been vacant since the retirement of Sardar Raza Khan last month. Prime Minister Imran Khan had proposed the name of Raja. Nisar Durrani and Shah Mohammad Jatoi have been nominated as ECP members from Sindh and Balochistan.