Chaudhry, who was sacked by former military ruler Pervez Musharraf for not endorsing the 2007 emergency, was received by scores of lawyers and members of the public when he drove to the apex court on Tuesday morning.
The crowd shouted slogans and showered rose petals on his official car as it drove him to the entrance of the building. Chaudhry, who was accompanied by his seven-year-old son Ahmad Balaj, was accorded a guard of honour by the Islamabad police.
On entering the court building, the Chief Justice shook hands with members of the staff before going to court room number 1. Witnesses said he was given a standing ovation inside the courtroom.
Later, Chaudhry administered the oath of office to Hamid Mirza, Pakistan's new chief election commissioner, during a ceremony held in the supreme court auditorium. The event was attended by a large audience including judges, lawyers, civil society representatives and Attorney General Latif Khosa.
Chaudhry had on Monday stayed away from an awards ceremony held in the presidency on the occasion of Pakistan Day, with officials saying he was preoccupied with preparing for cases. This was the first official event Chaudhry was invited to after his restoration.
Chaudhry and other judges who were deposed by Musharraf were reinstated by the Pakistan People's Party-led government last week following a countrywide protest by the lawyers' movement and the opposition Pakistan Muslim League-Nawaz.
In a significant move, Chaudhry segregated the judges who were sacked for defying the emergency imposed by Musharraf on November 3, 2007 and those who had endorsed the measure while constituting new benches of the apex court.
Some lawyers -- including Akram Sheikh, who has appeared in court on behalf of senior PML-N leaders -- have filed petitions asking the Supreme Court to prevent judges who endorsed the emergency from continuing in their positions.
The lawyers' movement had launched a struggle after Chaudhry was suspended from his position by Musharraf in March 2007. He was subsequently restored in July the same year but was sacked when Musharraf imposed emergency.
The lawyers continued to back Chaudhry, who toured the country to address rallies and meetings, and the movement eventually weakened Musharraf and paved the way for his ouster by the PPP and its former ally PML-N in August last year.
Observers have said PPP chief and President Asif Ali Zardari was reluctant to reinstate Chaudhry as he feared the top judge could scrap a controversial law passed by Musharraf to drop graft cases against PPP leaders.