After his completion of MSc in technology from the Banaras Hindu University, Krishan joined the CSIR. Soon after, quitting his job, he got completely involved in politics and subsequently became a parliamentarian representing INC (Indian National Congress). He was a member of the “Young Turk”, a contingent of the party, started by the then Prime Minister, Indira Gandhi. But he openly opposed the emergency imposed by Indira Gandhi and for his act; he was expelled from the party. A couple of years later, he got associated with the Janata Party in 1977.
He, along with Raj Narain and Madhu Limaye were responsible for the downfall of Morarji Desai government in 1979. In V.P. Singh government in 1990, he was appointed as the governor of Andhra Pradesh and he held that post for 7 long years ad in the process became India’s one of the longest serving governors. He held on to his governor’s post until he was made the Vice-President of India.
He was selected for the post of vice-president as the joint candidate by both the parties United Front and Indian National Congress. Thus, he remained vice-president of India from 1997 till his death.