After his initial postings as chief executive officer of a Zilla Parishad, Banthia was appointed collector, Bhandara. After a three-year stint, he took up a central deputation post as director of census operations under the ministry of home affairs, where he was promoted as registrar general and census commissioner and held the post till May 2005. In June 2005, he was appointed the chief technical advisor with the United Nations population fund. On 6 January 2010, he returned to the state government and was appointed commissioner, family welfare. Last year, he was promoted as additional chief secretary (public health).
