Irving Fields performs at Nino’s Tuscany Steakhouse in Midtown Manhattan in 2013. (Spencer Platt/Getty Images)

The music was played on jukeboxes, on bandstands and in the hotels of the Catskills during those years after World War II when many first- and second-generation American Jews no longer spoke Yiddish but had not yet forgotten its sound.

That era of transition came with a musical form all its own: the Yiddish or Jewish mambo, a mash-up of Jewish folk songs, Yiddish tunes and klezmer melodies with the Latin rhythms that took American ballrooms by storm in the 1940s and ’50s.

Among Yiddish mambo’s most exuberant exponents was Irving Fields, a pianist, bandleader, arranger and songwriter who made a winning contribution to the genre with his 1959 album “Bagels and Bongos.” Mr. Fields, 101, died Aug. 20 at his home in New York City. The cause was pneumonia, said his wife, Ruth Fields.

“Your Miami-bound snowbird grandparents weren’t the first Jews to embrace the mambo pace,” reads an online promotion for a remastered version of Mr. Fields’s album, curated by the nonprofit Idelsohn Society for Musical Preservation and released in 2005.

“Using Latin music as an idiom of Jewish expression, a new language of a hybridized, flexible Jewish identity was born,” the promo proclaims — and with numbers such as “Mazeltov Merengue” and “Miami Merengue,” it was “bound to shake some tuchuses enough to seriously throw off a game of shuffleboard.”

Mr. Fields spent very nearly a century in music, from his boyhood performances in the Yiddish theater of New York and under the acclaimed Jewish cantor Yossele Rosenblatt, to his time as leader of the crowd-pleasing Irving Fields Trio, to his decades as a pianist on the nightclub and lounge circuit.

Last year, he got a gig in New York at the Park Lane Hotel on Central Park South. At 99, he would station his walker next to the piano, shake off the arthritis in his fingers and take requests from patrons. He told the New York Times that he might be “the oldest pianist still working steady in the world,” a claim that could not immediately be verified, although it could not be disproved, either.

Adam Swanson, a pianist and historian of American popular music of the early 20th century, said in an interview that Mr. Fields was “one of the very last of the Tin Pan Alley songwriters.” He began studying music as a boy on the Lower East Side, where his parents, Russian Jews who had fled the pogroms, scraped together money for piano lessons.

The investment paid off when Izzy, as he was known, found work during the Depression as a pianist on cruise ships. During stops in San Juan and Havana, he acquired an abiding love of the rumba, the merengue, the cha-cha and other Latin rhythms. “Go figure,” Swanson said. “He loved it and made a lot of people happy with it.”

In the 1940s, Mr. Fields burst onto the scene as a songwriter with hits including “Miami Beach Rhumba,” popularized by bandleader Xavier Cugat, and “Managua, Nicaragua,” recorded by Guy Lombardo, Freddy Martin and Kay Kyser. Another of Mr. Fields’s numbers, “Chantez-Chantez,” was recorded by Dinah Shore and was featured in the 1963 film “Take Her, She’s Mine,” starring Jimmy Stewart and Sandra Dee.

Mr. Fields’s early work was not explicitly Jewish in nature. But Josh Dolgin, a Canadian producer and musician known as Socalled who melds hip-hop and klezmer, listens to “Miami Beach Rhumba” and hears the echoes of Russian folk music.

“It’s basically a klezmer riff,” Dolgin said in an interview. “His Yiddish soul just kept peeking out.”

Mr. Fields was neither the first nor the last songwriter of his era to combine Jewish and Latin music. But he made a notable entry with “Bagels and Bongos,” a title, he said, that came to him as he bit into a bagel with lox. The album, which sold a reported 2 million copies, included Latinized versions of standards such as “My Yiddishe Momme,” “Raisins and Almonds” and “Bei Mir Bist Du Schon.”

After “Bagels and Bongos,” Mr. Fields and his trio produced “More Bagels and Bongos” — “because the world needed more,” quipped Josh Kun, a member of the Idelsohn Society and a professor at the University of Southern California. The trio later made the albums “Pizzas and Bongos” (an homage to the Italian tradition), “Champagne and Bongos” (with Latin variations on French standards) and “Bikinis and Bongos” (with a Hawaiian twist).

In time, the allure of Latin music gave way to rock-and-roll, and Mr. Fields’s audiences drifted away from the cha-cha and merengue just as previous generations had abandoned the bulgar and freylekh dances, Dolgin said.

But Mr. Fields proved remarkably durable. He developed a savant-like repertoire that he unleashed, fueled by two-olive martinis, at venues including the Copacabana and the Plaza Hotel in New York, Caesars Palace in Las Vegas, and the Versailles Hotel in Miami.

On command, he could knock out standards as diverse as Beethoven’s “Für Elise,” “The Yellow Rose of Texas,” George Gershwin’s “Rhapsody in Blue” and “Fiddler on the Roof,” which he played with a Latin beat.

The music “just comes to me,” he told the Times. “It’s like God is in my mind.”

Mr. Fields was born Isidore Schwartz in New York City on Aug. 4, 1915. His mother was a homemaker, and his father was a carpenter and a singer in Jewish choirs.

Growing up, Mr. Fields preferred stickball to the piano, he recalled in an autobiography written with Tony Sachs, “The Pianos I Have Known.” His parents obliged him to continue his piano lessons, which eventually led him to the Eastman School of Music.

As a performer, he became known as Irving Fields, or even Campos El Pianista, “campos” being the Spanish word for “fields,” as in “meadows.”

Mr. Fields’s marriage to Jane Fields ended in divorce. Survivors include his wife of 34 years, the former Ruth Singer Dechowitz of New York City; two children from his first marriage, Diane Shaffran of Lawrenceville, Ga., and Mark Fields of New York City; two stepchildren, Penny Dechowitz and Peter Dechowitz, both of New York City; and numerous grandchildren and great-grandchildren.

As he aged, Mr. Fields endeavored to stay current with trends of the day, just as he had during the Latin craze. He learned piano versions of Beyoncé songs — to be prepared for requests from lounge patrons — and collaborated with Dolgin on the 2007 album “Ghettoblaster.” A ditty Mr. Fields composed in tribute to the riches of YouTube, where his music achieved a degree of immortality, attracted nearly 900,000 views on the website.

“He was just trying,” Dolgin observed, “to make it in America.”

An earlier version of this obituary incorrectly identified Josh Kun as a professor at the University of California. He is a professor at the University of Southern California.