Rajnath Singh was on Friday appointed as Minister of Defence in Prime Minister Narendra Modi's second Cabinet.
The BJP heavyweight headed the Ministry of Home Affairs in Modi's first tenure.
Terrorism in Jammu and Kashmir, incursion attempts by Pakistan and China, and the emergence of Islamic State were among the top challenges faced by Singh as Home Minister.
He represents the Lucknow Lok Sabha seat, a constituency he won for the second consecutive in recently-concluded Lok Sabha elections. Earlier, he represented Gautam Budhh Nagar in 2009.
A politician for over four decades, Singh is well known for maintaining cordial relations with political leaders irrespective of their parties.
Known for his excellent oratory skills, the 67-year-old leader started his career as an RSS volunteer and joined politics in 1974 as secretary of Jana Sangh's Mirzapur unit. He was later elected as an MP from Mirzapur in 1977.
He also served as the Chief Minister of Uttar Pradesh and as a Cabinet Minister during Atal Bihari Vajpayee's government.
One of the senior most leaders in the Modi Cabinet, he has also served as the president of the BJP twice, 2005 to 2009 and 2013 to 2014.
The Rashtrapati Bhavan on Friday announced portfolios for 24 cabinet ministers, 9 ministers of state with independent charge and 24 Ministers of State (MoS) in Union Cabinet for the 17th Lok Sabha.
Prime Minister Modi and his Council of Ministers on Thursday took the oath of office at Rashtrapati Bhavan for a second consecutive term.
( With inputs from ANI )