Sahrif along with the parliamentarians was administered the oath by outgoing National Assembly Speaker Fehmida Mirza shortly after noon as the new National Assembly gathered for its first session amidst tight security.
The PML-N chief flew from Lahore to Rawalpindi with close aides before driving to the capital to join the session of the new National Assembly that is set to anoint him as Prime Minister for a record third term.
Hundreds of security personnel were deployed to protect the "Red Zone" in the heart of Islamabad as military helicopters carried out aerial surveillance of the city.
He was then driven in a motorcade to Islamabad to attend the session of the National Assembly or lower house of parliament.
Sharif, 63, who was wearing a white shalwar-kameez and a grey waistcoat, sat in a front row of the House with senior PML-N leader Chaudhry Nisar Ali Khan.
After the recitation of a verse from the Quran, the outgoing Speaker administered the oath to the lawmakers.
Mirza announced that the new Speaker and Deputy Speaker would be elected on June 3 and then invited the new members to sign the roll of the National Assembly.
The election of the premier is scheduled for June 5 as Sharif's election as leader of the House is a foregone conclusion as the PML-N has over 180 members in the 342-strong National Assembly.
Speaking briefly with the media at the Rawalpindi airport, Sharif expressed his satisfaction at the "peaceful transition" ushered in by the May 11 general election.
He thanked God for giving an opportunity to the people to bring about a change through elections.
"I think it is lucky that my party and I had a role in this movement. It is a very good thing that there is a peaceful transition in Pakistan," he said.