Merchant, 67, had undergone a minor surgery shortly before his death, NDTV channel reported late Wednesday.
It was the second major blow for India's entertainment industry in a single day, with film star-turned-politician Sunil Dutt also passing away due to a heart attack earlier Wednesday in Mumbai.
Ismail Merchant was the frugal movie mogul in Hollywood who could convince top stars like Paul Newman and Anthony Hopkins to slash their staggering fees. He was a dreamer who dreamt films - big, sophisticated, thought-provoking and daring films. And his powers of persuasion were legendary.
He succeeded in getting globally acclaimed authors Anita Desai and V.S. Naipaul to part with the filmmaking rights of their respective novels. Not too many people could've done that.
Born Dec 25, 1936, Merchant's training in business management held him in good stead. Some though said the cooking did the trick.
In fact many of his friends believed Merchant was as good a cook as he was a film producer. His cookbook "Ismail Merchant's Indian Cuisine" is a perennial seller.
For long he shied away from direction and chose to do what he knew best: produce films.
As a producer he collaborated with director James Ivory and screenwriter Ruth Prawer Jhabvala for what was one of most creatively fulfilling teams in world cinema.
The trio's creations include "The Householder" (1963), "Shakespearewallah" (1965), "The Guru" (1969), "Bombay Talkies" (1970), "Heat & Dust" (1983), "The Bostonians" (1984), "A Room With A View" (1986), "Mr & Mrs Bridge" (1990), "Howards End" (1992) and "The Remains Of The Day" (1993).
Each of these are monuments of collaborative creation and a result of Merchant's visionary approach to cinema.
How he met his long-standing director Jim Ivory makes an interesting story.
Ivory was in India to shoot a documentary commissioned by Asia Society. He befriended Merchant and continued to make films for the producer both in India and outside.
Some believed Merchant was a failure as a director. His two feature films as director, "In Custody" and "The Mystic Masseur" (both literary adaptations), are regarded as honourable failures.
Merchant made the notable short film "The Creation Of A Woman" (1960) which was nominated for an Oscar. He then went on to make another short film "Mahatma & The Mad Boy" in 1973 and the documentary "Courtesans of Bombay" in 1982 before taking to feature film direction.
When "The Guru" and "Bombay Talkies" flopped, Merchant moved his cinema's milieu away from India. But his heart remained in the country. To the end he was a Mumbai boy dreaming epic dreams.