This article originally appeared on BBC.com
His wife, Barbara, said he died on Tuesday at their home in Vermont, after suffering from leukaemia.
Kinnell was among the most celebrated poets of his time and wrote more than a dozen books spanning five decades.
He won the Pulitzer for his 1982 book Selected Poems.
The collection also won the National Book Award for Poetry, sharing the honour with contemporary Charles Wright.
His other best-known works include The Book of Nightmares, inspired by the horror of the Vietnam war, When One Has Lived a Long Time Alone and Mortal Acts, Mortal Words.
One his most famous poems is The Bear, telling of a hunter who, after consuming animal blood and excrement, comes to identify with his prey.
Other notable poems include After Making Love We Hear Footsteps and When the Towers Fell, about the September 11 terrorist attacks in New York.
Born in Providence, Rhode Island, on 1 February 1927, Kinnell was the son of immigrants from Scotland and Ireland.
The Los Angeles Times reported the poet once told students he was “a very silent child, almost mute”.
“I developed a big sense of isolation from others… Gradually I felt that if I was ever going to have a happy life, it was going to have to do with poetry,” he said.
He attended Princeton University, where he was roommates with future US poet laureate WS Merwin, who introduced him to the works of WB Yeats.
Merwin told Associated Press he and Kinnell had been “like brothers” and remembered his friend as a “very generous soul”.
He praised the poet’s work as “warm hearted” and the creations of “someone who was independent but felt sympathy with other people”.
Kinnell’s breakthrough poem came in 1960, with The Avenue Bearing the Initial of Christ Into the New World – a 14-part work about Avenue C in Manhattan and the people that walked the street.
He served as poet laureate for Vermont from 1989 to 1993, and moved there in 2005.
The Academy of American Poets later gave him the Wallace Stevens Award for lifetime achievement in 2010.
He married his first wife, Spanish translator Ines Delgado de Torres, in 1965 and had two children, Fergus and Maud, but divorced 20 years later. He married second wife Barbara in 1997.