President Mamnoon Hussain approved Jillani's elevation to the post. His appointment will come into effect from December 12, a day after Chaudhry, the longest serving Chief Justice, retires.
"The President has approved...the appointment of senior most judge Justice Tassaduq Jillani as the Chief Justice of Pakistan with effect from December 12," an official said.
Jillani is a close relative of former premier Yousuf Raza Gilani and a confidante of the outgoing Chief Justice. He is often described as a "gentleman judge" and will serve for nearly seven months.
Chaudhry has built a reputation by strengthening the judiciary, often through direct confrontation with the civilian government and the powerful military.
His actions led to the ouster of former Prime Minister Gilani after he refused to write to Swiss authorities to reopen graft cases against then President Asif Ali Zardari. Many critics had then described it as a "judicial coup".
The slot of the Chief Justice has to automatically go to the senior most judge after the retirement of the incumbent. Neither the President nor the Prime Minister or the government has any role in the nomination of the Chief Justice.
Only the President is to administer oath to the new Chief Justice as per the Constitution.
Born on July 6, 1949, Jillani, hailing from Multan in Punjab, will retire on July 6, 2014, after reaching the age of 65.
After his superannuation, Justice Nasirul Mulk, from Khyber-Pakhtunkhwa, who would then be the senior most judge of the apex court. If he is appointed the Chief Justice, his tenure will last less then 14 months.