newspaper during 1988-2011, was admitted to a hospital in Karachi more than a week ago with a chest ailment.
Besides his columns laced with his acerbic wit and his forthright take on pressing issues facing Pakistan, Cowasjee was known for his social activism and philanthropy.
He was born into a prominent Parsi business family of Karachi on April 13, 1926.
He joined his family's shipping business after completing his education from Bai Virbaiji Soparivala Parsi High School and DJ Sindh Government Science College.
He had two children with his late wife Nancy Dinshaw.
In December 2011, Cowasjee decided to stop writing his weekly column.
"Now, old at 85, tired, and disillusioned with a country that just cannot pull itself together in any way and get on with life in this day and age, I have decided to call it a day," he wrote in his farewell column.
The Cowasjee Foundation has funded the higher education of numerous students.
Several of Karachi's hospitals too are beneficiaries of the Foundation.
Many Pakistanis took to Twitter to pay tribute to Cowasjee.
"Very few people know Ardeshir Cowasjee quietly tried to support upright, young (journalists) financially," tweeted Abbas Nasir, a former editor of Dawn.
"Sad to hear that one of Pakistan's finest and most conscientious columnists, Ardeshir Cowasjee, has passed away. May his soul rest in peace," said columnist Nadeem F Paracha in a tweet.
President Asif Ali Zardari and Prime Minister Raja Pervez Ashraf were among the politicians who paid tribute to Cowasjee.
Expressing sorrow at the death, Zardari paid tribute to the services of Cowasjee in the field of journalism.
Ashraf said that in Cowasjee's death, the "nation has lost a true, patriotic Pakistani and a journalist of high calibre and repute whose contributions will be long remembered".
He appreciated that Cowasjee "always espoused the righteous and just causes, no matter how tough the going was".