NEW YORK — Rod McKuen, the husky-voiced “King of Kitsch” whose music, verse and spoken-word recordings in the 1960s and ’70s won him Oscar nominations and made him one of the best-selling poets in history, has died. He was 81.

McKuen died Thursday morning at a rehabilitation center in Beverly Hills, California, where he was treated for pneumonia and had been ill for several weeks and unable to digest food, said his half-brother, Edward McKuen Habib.

Until his sabbatical in 1981, McKuen was an astonishingly successful and prolific force in popular culture, turning out hundreds of songs and poems and records, including the Academy Award-nominated song “Jean” for the 1969 film “The Prime of Miss Jean Brodie.”

Sentimental, earnest and unashamed, he conjured a New Age spirit world that captivated those who didn’t ordinarily like “poetry” and those who craved relief from the war, assassinations and riots of the time.

“I think it’s a reaction people are having against so much insanity in the world,” he once said. “I mean, people are really all we’ve got. You know it sounds kind of corny, and I suppose it’s a cliche, but it’s really true; that’s just the way it is.”

His best-known songs, some written with the Belgian composer Jacques Brel, include “Birthday Boy,” “A Man Alone,” “If You Go Away” and “Seasons In the Sun,” a chart-topper in 1974 for Terry Jacks. He was nominated for an Oscar for “Jean” and for “A Boy Named Charlie Brown,” the title track for the Peanuts movie.

Frank Sinatra, Madonna, Dolly Parton and Chet Baker were among the many artists who recorded his material, although McKuen often handled the job himself in a hushed, throaty style he honed after an early life as a rock singer cracked his natural tenor.

McKuen is credited with more than 200 albums – dozens of which went gold or platinum – and more than 30 collections of poetry. Worldwide sales for his music top 100 million units while his book sales exceed 60 million copies.

He was particularly productive in the late ’60s, releasing four poetry collections, eight songbooks, the soundtracks to “Miss Jean Brodie” and “A Boy Named Charlie Brown” and at least 10 other albums.

Around the same time, his “Lonesome Cities” album won a Grammy for best spoken word recording and Sinatra commissioned him to write material for “A Man Alone: The Words and Music of Rod McKuen.”

With his sharply parted blond hair, sneakers and jeans, McKuen was recognized worldwide in every medium: movies, music, books, television, stage.

When not writing or recording, he appeared on “The Tonight Show” with Johnny Carson and other talk show programs, formed a film production company with Rock Hudson and toured constantly until he took an extended break in 1981.

“I was tired. I peaked. I left when I was on top,” McKuen told the Chicago Tribune in 2001. “One year, I did 280 concerts. I was all over the world. I went to cities I never saw. I’d go to sleep and then it was time to get up and be in the next town.”

McKuen sometimes wrote a poem or song a day. He had no formal musical or literary training and prided himself on writing verse that anyone could understand.

Among his most quoted phrases were “Listen to the warm” and “It doesn’t matter who you love, or how you love, but that you love.”

McKuen, however, didn’t receive universal acclaim. Newsweek dubbed him “The King of Kitsch,” while the magazine Mademoiselle preferred “Marshmallow Poet.” And a National Lampoon parody interspaced mock verses with dollar signs.

McKuen’s childhood was as hard as his lyrics were soft. Born in Oakland in 1934, McKuen’s father left when he was a baby, and he was terrified of his alcoholic stepfather.

By 11, McKuen had run away. He spent his teens doing everything from ranching to roping horses in a rodeo, and he wrote poetry in his free time.

After serving as a propaganda writer in the Korean War, McKuen wound up in San Francisco, where his friend Phyllis Diller helped him find work in the growing nightclub scene.

He went on to sing with the Lionel Hampton band, acted in a handful of movies and TV shows, read poetry on the same bill as Jack Kerouac and other Beat writers and had a minor hit single in the early 1960s with the dance parody “Oliver Twist.”

While living in France, he met Brel and began a friendship that set him on his way to superstardom. His English-language adaptations of Brel’s songs included the hit “Seasons In the Sun” and the pop standard “If You Go Away.”

Without critical approval or a book or recording contract, McKuen proved that an artist could thrive on word of mouth alone. He sang in bowling alleys to promote “Oliver Twist,” which cracked the Billboard top 100. His self-published collection of poems and lyrics, “Stanyan Street and Other Sorrows,” sold tens of thousands of copies before Random House acquired it.

McKuen slowed down over the second half of his life, and many of his books fell out of print. However, he continued to publish poetry, remastered old musical recordings and gave occasional concerts. He provided voiceovers for the Disney movie and TV series “The Little Mermaid” and appeared at Carnegie Hall in 1995 for an 80th birthday tribute to Sinatra. Artists continued to record his songs, including the former Gene Ween, Aaron Freeman, who in 2012 released an album of McKuen covers called “Marvelous Clouds.”

McKuen did at times take on social and political issues. He opposed the Vietnam War, wrote a poem about the Watergate scandal and supported civil rights and equal rights for gays.