He represented the Banjar assembly constituency in Himachal Pradesh Assembly.
He was a member of the Kullu royal family and was in the BJP before he switched over to the Congress ahead of 2002 state assembly elections. He was a three-time MLA and also served as a minister twice.
Congress Vice President Rahul Gandhi condoled his death and termed it as a big loss for the government and people of the state.
“Karan Singhji’s untimely demise is a big loss for the government and people of Himachal. His guidance and leadership will be missed. My condolences to his family,” he said on Twitter.
Himachal Pradesh Chief Minister Virbhadra Singh also condoled his death.
The state government is arranging for taking the body to Kullu by a helicopter. He will be created later in the day in his native place, his brother said.
Former chief minister Shanta Kumar, Assembly Speaker BBL Butail, ministers, MLAs and prominent leaders have expressed grief over Singh’s demise.