Four information commissioners also took the oath of office, a statement issued by the President's office said.
Bhargava was administered the oath of office by President Ram Nath Kovind at a ceremony in Rashtrapati Bhavan, a statement issued by the President's office said.
Bhargava was working as the Information Commissioner in the CIC.
Former chairperson of the Central Board of Indirect Taxes and Customs (CBIC) Vanaja N Sarna, former IFS officer Yashwardhan Kumar Sinha, the then disinvestment secretary Neeraj Kumar Gupta and former law secretary Suresh Chandra were administered the oath of office by Bhargava at the CIC office, officials said.
Sarna is the only woman in the CIC. She is a 1980-batch retired Indian Revenue Service (Customs and Central Excise) officer.
Sinha is a 1981-batch Indian Foreign Service (retired) officer who was the Indian high commissioner in the United Kingdom.
An alumnus of St Michael's High School in Patna and St Stephen's College in Delhi, Sinha had served a number of important postings in the Ministry of External Affairs, including the crucial Pakistan-Afghanistan-Iran division, which he headed for four years as the additional secretary.
Gupta, a 1982-batch IAS officer, retired as a secretary from the Department of Investment and Public Asset Management.
Chandra, who had been the officer on special duty to former law minister Arun Jaitley and law minister Ravi Shankar Prasad, served as the law secretary between June 2016 and November 2018.