Karan Singh was born in Cannes, France into the Dogra dynasty, which was the Dogra Rajput family that ruled the Kingdom of Jammu and Kashmir. Singh was educated at Doon School, Dehra Dun, and received a B.A. degree from Jammu and Kashmir University, Srinagar, and subsequently an M.A. degree in Political Science and a Ph.D. degree from Delhi University
He is a poet and authored poetry book too and his poems featured in the poetry anthology, The Dance of the Peacock: An Anthology of English Poetry from India, featuring 151 Indian English poets, edited by Vivekanand Jha and published by Hidden Brook Press,Canada.
1949, at age of eighteen, Singh was appointed as the regent of Jammu and Kashmir state after his father stepped down as the ruler, following the state's accession to India. He served successively as regent, the first and last Sadr-i-Riyasat, and governor of the state of Jammu and Kashmir from 1965 to 1967.
In 1967, he resigned as Governor of Jammu and Kashmir, and became the youngest-ever member of the Union Cabinet, holding the portfolios of Tourism and Civil Aviation between 1967 and 1973. Two years later, he voluntarily surrendered his privy purse, which he had been entitled to since the death of his father in 1961. He placed the entire sum into a charitable trust named after his parents. In 1971, he was sent as an envoy to the Eastern Bloc nations to explain India's position with regard to East Pakistan, then engaged in civil war with West Pakistan. He attempted to resign following an aircraft crash in 1973, but the resignation was not accepted. The same year, he became the Minister for Health and Family planning, serving in this post until 1977.
Following the Emergency, Karan Singh was elected to the Lok Sabha from Udhampur in 1977 on a Congress ticket [the party had not split into Congress(I) and Congress(U) factions till then, and became Minister of Education and Culture in 1979 as part of Charan Singh's cabinet, representing Congress(U), which had split from Indira's Congress. He contested the 1980 Lok Sabha election on a Congress(U) ticket and won. In 1989–1990, he served as Indian Ambassador to the US, and this experience became the subject of a book he wrote, "Brief Sojourn."
From 1967 to 1984 Karan Singh was a member of the Lok Sabha. In 1984, he contested the Lok Sabha polls as an independent candidate from Jammu but lost the election. He was a member of the Rajya Sabha first representing J&K National Conference – a Muslim dominated state party active in northern Indian state of Jammu & Kashmir – from 30 November 1996 to 12 August 1999 and currently is a Rajya Sabha member from 28 January 2000 representing INC. He has served as Chancellor of Banaras Hindu University, Jammu and Kashmir University, Jawaharlal Nehru University, and NIIT University.