He was born in Sandhwan, Faridkot district on 5 May 1916 to Kishan Singh and Mata Ind Kaur, a Ramgarhia couple of a small village, Sandhvan, near Kot Kapura, in the princely state of Faridkot. Kishan Singh was the village carpenter. Additionally, he had his own small acreage to till. He was a devout Sikh and was known in the countryside for his simple and upright manner. Zail Singh was named Jarnail, meaning “General”, but as a young man, he changed his first name to Zail after being imprisoned several times for opposing the rule of the maharajah of Faridkot. He was a Sikh by religion, was given the title of Giani, as he was educated and learned about Guru Granth Sahib at Shaheed Sikh Missionary College in Amritsar.
Zail Singh was elected as a Congress Chief Minister of Punjab in 1972. He arranged massive religious gatherings, started public functions with a traditional Sikh prayer, inaugurated a highway named after Guru Gobind Singh, and named a township after the Guru's son. He created a lifelong pension scheme for the freedom fighters of the state. He repatriated the remains of Udham Singh from London, armaments and articles belonging to Guru Gobind Singh.
In 1982, he was unanimously nominated to serve as the President. Nonetheless, some in the media felt that the President had been chosen for being an Indira loyalist rather than an eminent person. "If my leader had said I should pick up a broom and be a sweeper, I would have done that. She chose me to be President," Singh was quoted to have said after his election. He took the oath of office on 25 July 1982. He was the first Sikh to hold the office. He served beside Gandhi and protocol dictated that he should be briefed every week by her on the affairs of the state. On 31 May 1984, day before Operation Blue Star, he met with Gandhi for more than an hour, but she omitted even sharing a word about her plan. Following the operation he was pressured to resign from his post by Sikhs. He decided against resignation fearing to aggravate the situation on advice from Yogi Bhajan. He was subsequently called before the Akal Takhat to apologize and explain his inaction at the desecration of the Harimandir Sahib and killing of innocent Sikhs. Indira Gandhi was assassinated on 31 October in the same year, and he appointed her elder son Rajiv Gandhi as Prime Minister. Also, in 1986 he exercised the Pocket vetowith respect to the Indian Post Office Bill, passed by Rajiv Gandhi, imposing restrictions on the freedom of press and hence, was widely criticised.
Singh used a pocket veto to refuse assent to the "Post Office Bill" in 1986 to show his opposition to the bill. The bill was later withdrawn by the V. P. Singh Government in 1990.
