“DAMN.,” which featured Rihanna and U2, along with kinetic production from Sounwave and Mike WiLL Made-It, among others, topped the charts and was among last year’s most-streamed albums, while also tackling thorny issues both personal and political, including race, faith and the burdens of commercial success. Though his work is often serious — and searing — Mr. Lamar, a dense and bruising lyricist, has managed to become a pop-cultural juggernaut as well, performing during halftime of this year’s college football national championship and overseeing the soundtrack for “Black Panther.”
The music finalists, selected by a five-person jury and then presented to the board for a winner selection, also included the composer Michael Gilbertson’s “Quartet” and the singer and composer Ted Hearne’s “Sound From the Bench.”
David Hajdu, one of the music jurors this year and a critic for The Nation, said that the group considered more than 100 compositions, including “some pieces of classical music that drew upon hip-hop as a resource,” leading to a philosophical discussion among the jurors about what could be considered.
“That led us to put on the table the fact that this sphere of work” — rap music — “has value on its own terms and not just as a resource for use in a field that is more broadly recognized by the institutional establishment as serious or legitimate,” he said.
When someone mentioned Mr. Lamar’s “DAMN.,” there was “quite a lot of enthusiasm for it,” Mr. Hajdu said, though some members of the jury were less familiar with hip-hop than others. (The jury also included the violinist Regina Carter; Paul Cremo of the Met Opera commissioning program; Farah Jasmine Griffin, a Columbia professor of English and African-American studies; and the composer David Lang.)
“But we listened to it and there was zero dissent,” Mr. Hajdu said. “A lively and constructive conversation, but no dissent.”
He added: “It was a beautiful moment. I left the deliberations on a cloud.”
The news of the prize sent a jolt through the classical music world, where living composers often struggle to be heard — competing not only against those who work in more popular genres, but also the long-dead greats who make up the classical canon. Some pooh-poohed Mr. Lamar’s win — one classical composer called it “insulting” on his Facebook page — but many others embraced it.
Caroline Shaw, a frequent collaborator of Kanye West’s whose “Partita for 8 Voices” won the Pulitzer in 2013, posted a YouTube video of Mr. Lamar on her Twitter feed with one word: “Yes.”
Mr. Hearne, whose cantata “Sound From the Bench” was a finalist, praised the decision to award the Pulitzer to Mr. Lamar, calling him “one of the greatest living American composers, for sure.”
“The work that’s on that album is every bit as sophisticated and experimental as any music,” he said in a telephone interview. “The idea that that’s not classical music, or that’s not experimental music, or that’s not art music is completely unfounded.”
It was not until 1997 that the Pulitzer Prize for music went even to a jazz work: Wynton Marsalis’s oratorio “Blood on the Fields.” In 1965, the Pulitzer jurors recommended awarding a special citation to Duke Ellington, but were rejected.
Mr. Hadju, the juror, said that in recent years, those behind the Pulitzers have sought to “assertively think and listen more expansively, with more open ears,” pointing to wins in the music category by the experimental jazz musicians Ornette Coleman in 2007 and Henry Threadgill in 2016. Other popular musicians have been recognized by the Pulitzers with special awards for their influence, including Bob Dylan, who also won a Nobel Prize in Literature; Lin-Manuel Miranda’s hip-hop musical “Hamilton” won in the Pulitzer drama category two years ago.
And while “DAMN.” has sold more than 3.5 million albums, including digital streams, since its release, according to Nielsen, “There was no talk about recognizing something that was already popular,” Mr. Hajdu said. “Just: ‘Listen to this — this is brilliant.’ This is the best piece of music.”