The 66-year-old actor is survived by estranged wife Nandita and son Ishsan.
"I am in shock right now. It's unbelievable. He passed away around 6-6.30 AM. He was lying on the kitchen floor," Nandita told PTI.
"I can't talk now. I am at Cooper hospital for the postmortem," she further said.
Prime Minister Narendra Modi condoled Puri's demise and recalled his long career in theatre and films.
Remembering him as a versatile actor Gandhi said, "Om Puri was a gifted actor and socially-conscious human being. Indian film industry has lost a pillar."
Apart from winning several accolades, including two National Awards for "Arohan" and "Ardh Satya", he was honoured with the Padmi Shri, the country's fourth highest civilian award in 1990.
Hailing from Ambala in Haryana, Puri studied at the prestigious Film and Television Institute of India (FTII) in Pune. He was also an alumnus of the 1973 class of the National School of Drama, where Naseeruddin Shah was a fellow student.
From Bollywood to Hollywood, from independent to art films, Puri gave several acclaimed performances.
A critically acclaimed actor, Puri featured in films like "Ardh Satya", "Jaane Bhi Do Yaaron", "Mirch Masala", "Aakrosh", "Paar", "Maachis" and others.
His other notable films include "Bhavni Bhavai", "Sandgate, "Dharavi", "Gupt", "Dhoop", "Yuva", "Don" and "Agneepath".
More recently, he was seen in movies like the Salman Khan-starrer "Bajrangi Bhaijaan", and "Ghayal Once Again".
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Meanwhile, several celebrities like Anupam Kher, Ashok Pandit, Shabana Azmi, Prakash Jha and others went to Puri's home and hospital to pay their last respects.
Azmi said in a tweet that Puri's body will be taken to his home in 'Trishul' building in suburban Mumbai after the postmortem and the funeral will be held at the Oshiwara crematorium this evening.
"Om Puri undergoing postmortem at Cooper Hospital. Will be taken to Trishul around 3pm Funeral at Oshiwara electric crematorium around 6pm," she posted on twitter.
