Newly-appointed adviser on finance, Dr Abdul Hafeez Sheikh, took charge of his post on Saturday.
The government notified his appointment as adviser to the prime minister on finance, revenue and economic affairs a day earlier.
Dr Shaikh, a political economist of international repute with over 30 years of experience, has served as the finance minister from 2010 to 2013.
He holds a PhD in economics. Dr Shaikh taught at Harvard University and worked at the World Bank for several years, advising 21 countries, including a stint as World Bank country head in Saudi Arabia.
His appointment comes at a critical time in Pakistan when the value of the rupee has depreciated to a historic low and the economy is beset by inflation and debt.
Dr Shaikh will serve as Adviser to the Prime Minister with the status of Federal Minister.