In a ceremony held at the Raj Bhavan here today, Rao took charge as the Governor of Maharashtra.
Chief Justice of the Bombay High Court Justice Mohit Shah administered him the oath of the office, while Chief Secretary Swadhin Kshatriya read out the warrant of Rao's appointment issued by the President of India.
Among those present on the occasion were Rao's wife Vinoda Rao, Chief Minister Prithviraj Chavan, Deputy Chief Minister Ajit Pawar, Telangana BJP chief Kishan Reddy, Union Minister for Road Transport and Highways Nitin Gadkari, BJP MPs Vijay Goyal and Kirit Somaiya and Mumbai police Chief Rakesh Maria, among others.
After the swearing-in ceremony, Rao was given the ceremonial Guard of Honour by the Indian Navy at Raj Bhavan.
Rao has taken over from Gujarat Governor Om Prakash Kohli, who was given additional charge as the Governor of Maharashtra following the resignation of Sankaranarayanan, after he was transferred to Mizoram by the Central government.
73-year-old Rao, who hails from Karimnagar district of Telangana, has served as the Minister of State for Home in the Atal Bihari Vajpayee government.
After schooling in his native district and intermediate in Hyderabad, he completed his graduation in science from Maharashtra. He also did LLB from Osmania University in Hyderabad and was a practicing lawyer before he became active in the Jan Sangh.
He was elected thrice to the undivided Andhra Pradesh Assembly in 1985, 1989 and 1994 from Metpalli in his native Karimnagar district.
Rao was elected to the 12th and 13th Lok Sabha from Karimnagar in Andhra Pradesh and found a berth in Vajpayee's Cabinet. He however, lost the recent Lok Sabha election from Karimnagar.