He was 74.
D'Monte was admitted to the Lilavati Hospital in suburban Bandra sometime back where he breathed his last on Saturday evening, his friend said.
In a career spanning several decades, he served as the resident editor of Mumbai editions of The Times of India and The Indian Express, he said.
Besides a career in journalism, he had a keen interest in environmental issues and took some initiatives for the cause, he added.
Meanwhile, former Union minister Jairam Ramesh expressed grief over D'Monte's demise and appreciated his work towards environmental issues.
Ramesh said he knew D'Monte very well for over three decades.
"He was among India's earliest environmental journalists and became one of the most eminent of them," the former environment and forest minister said.
"His writings, I know, had considerable influence on government policy. He combined passion with solid research. He mentored a number of youngsters in the field of environmental journalism. He and I disagreed at times but retained a great fondness for each other," he said.
The minister said he was sure D'Monte will continue to inspire those committed to ensuring ecologically sustainable growth.