George Wein, an impresario whose Newport jazz and folk festivals were the scenes of musical milestones, including the revival of Duke Ellington’s career and Bob Dylan’s epochal decision to “go electric” in 1965, and whose idea for outdoor performances became the model for Woodstock, Lollapalooza and countless other live-performance extravaganzas, died Sept. 13 at his apartment in Manhattan. He was 95.

His publicist, Carolyn McClair, confirmed the death but did not give a cause.

An innovative and tireless organizer, Mr. Wein (pronounced Ween) may have presented more musicians to more people than anyone else in history. He launched the Newport Jazz Festival in 1954, the folk festival in 1959 and later developed the New Orleans Jazz and Heritage Festival, the Playboy Jazz Festival in Los Angeles and dozens of others across Europe, Asia and North America.

By the 1980s, Mr. Wein was producing more than 50 major events a year, making him the world’s leading jazz promoter and largest employer of jazz musicians.

He “can justifiably claim to have invented, developed and codified the contemporary popular music festival,” said critic Gene Santoro, writing in the Nation in 2003. “Without Wein, everything from Woodstock to Jazz at Lincoln Center might have happened differently — if it happened at all.”

A capable jazz pianist, Mr. Wein began his career as a musician. After opening a jazz club in Boston in 1950, he met a music-loving couple, Elaine and Louis Lorillard, the latter an heir to a tobacco fortune. They suggested that a jazz program might enliven the summer season in the Gilded Age resort of Newport, R.I., where they lived. The Lorillards put up the money and left the arrangements to Mr. Wein.

Using the Tanglewood summer program of the Boston Symphony as a loose guide, Mr. Wein devised the idea of outdoor jazz performances in Newport. The First Annual American Jazz Festival, as he called it, took place on July 17-18, 1954, on the grounds of a tennis club.

“At the beginning,” he told Billboard magazine in 2004, “I called it ‘the first annual’ when we didn’t know if there was going to be a second.”

The debut effort turned a profit of $142.50 — but only because Mr. Wein did not claim his producer’s fee of $5,000.

“Dowagers and debutantes, sailors and their gals . . . mingled with thousands of hepcats,” the Providence Journal noted. “Never before has there been such an assemblage at Newport.”

Elaine Lorillard maintained that she and her husband, who were divorced in 1959, were the sole founders of the Newport Jazz Festival and that Mr. Wein was simply a “stage manager.”

Yet it was Mr. Wein who hired the musicians, including Ella Fitzgerald, Billie Holiday, Dizzy Gillespie, Gerry Mulligan and Lester Young in the first year alone. He organized every aspect of the event, from staging to transportation to ticket sales. As a result, he was credited with taking jazz out of urban nightclubs and into the sunlight, introducing it to new audiences at a time when rock-and-roll was beginning to take over the airwaves.

Within two years, the Newport Jazz Festival had become so well established that it formed the backdrop of the 1956 film “High Society,” starring Frank Sinatra, Bing Crosby, Grace Kelly and Louis Armstrong. Scenes from the 1958 festival were featured in the well-regarded documentary film “Jazz on a Summer’s Day,” by Bert Stern and Aram Avakian.

One of the festival’s mythic moments occurred July 7, 1956, when Mr. Wein first presented Ellington at Newport. That night, Ellington’s band performed a seldom-played two-part composition called “Diminuendo and Crescendo in Blue.”

As Ellington lent encouragement from the piano, tenor saxophonist Paul Gonsalves stepped up and played 27 blistering choruses, going on for more than five minutes as the crowd was stirred into a roaring frenzy.

Within weeks, Ellington — considered a fading figure from the past before Newport — appeared on the cover of Time magazine. The album “Ellington at Newport,” featuring Gonsalves’s solo, became the best-selling recording of his career.

Afterward, Ellington often said, “I was born in 1956 at the Newport festival.”

Mr. Wein branched out from jazz in 1959, capitalizing on a growing roots-music movement to introduce the Newport Folk Festival, with performances by Pete Seeger, Odetta, the Kingston Trio, the Weavers and the teenaged Joan Baez.

The folk festival had its most illustrious — or most notorious — moment in 1965, when Dylan walked onstage with an electric guitar. Folk purists considered his turn toward amplified, rock-influenced music nothing less than a betrayal.

“The audience, which was shocked into silence for a moment, quickly began to register its disapproval,” Mr. Wein wrote in his 2003 autobiography, “Myself Among Others.” “People began booing; there were cries of ‘Sellout!’ ”

Seeger pleaded, “Make it stop!”

Dylan’s performance, in which he embraced the technology and rebellious style of the rock-and-roll generation, became known as “the night that split the ’60s,” according to music historian Elijah Wald.

“The problem was not simply electricity,’’ Wald wrote in his 2015 book “Dylan Goes Electric!” “It was a broader confluence of conflicts: pop music versus roots music; commercial confections versus communal creations; escapism versus social involvement.’’

Over the years, Mr. Wein’s festival helped propel the careers of many musicians, including Ray Charles, Muddy Waters and singers Aretha Franklin and Mahalia Jackson.

In 1969, Mr. Wein yielded to popular tastes by presenting several rock acts, including Jethro Tull, Led Zeppelin, and Sly and the Family Stone — an occasion he later described as “four of the worst days of my life.”

He stood in the wings beside Miles Davis, the jazz trumpeter renowned for “Birth of the Cool” and “Kind of Blue” in the 1940s and 1950s, as the rock acts took the stage. Within a month, Davis formed a new band and, for the next 20 years, performed a hybrid form of music based on the amplified and electric instrumentation of rock.

“Jazz — the music I loved — was being poisoned and stamped out,” Mr. Wein wrote, “and I had served as an unwitting, but willing accomplice in the murder.”

On two occasions, rioting nearly brought the Newport festival to an end, in 1960 and again in 1971, when rowdy crowds broke down fences. The city council banned the festival from Newport, and it would be a decade before Mr. Wein returned.

In the interim, Mr. Wein moved the festival to New York, where it was named after various sponsors, including Kool cigarettes and the JVC electronics company. He made a triumphant return to Newport in 1981, and versions of his festival have been held in both Newport and New York most years since then.

By the late 1950s, Mr. Wein had begun to export his festival formula to other locales. In 1970, he took over the production of a struggling festival in New Orleans. He renamed it the New Orleans Jazz and Heritage Festival, and it went on to become one of the country’s most popular outdoor celebrations of music and food, attracting hundreds of thousands of visitors a year.

Mr. Wein and his company, Festival Productions, became globally known, with festivals in France, England, Germany and the Netherlands, as well as in Asia. In 1978, he produced a jazz festival at the White House, with President Jimmy Carter standing alongside Dizzy Gillespie, half-singing, half-speaking Gillespie’s comical bebop tune “Salt Peanuts” until the president dissolved in laughter.

George Theodore Wein was born Oct. 3, 1925, in Lynn, Mass. He grew up in the Boston suburb of Newton, Mass., where his father was an ear, nose and throat doctor.

Mr. Wein began piano lessons at 8 and, while still in high school, organized his first jazz band. He served in an Army engineering unit in Europe during World War II.

His family wanted him to study medicine, but jazz kept drawing him in. He played piano while attending Boston University, from which he graduated in 1950. That year, Mr. Wein opened his Storyville jazz club in Boston, where he presented Holiday, Fitzgerald, Charlie Parker and other musical stars.

“I knew the limits of my musical talents,” Mr. Wein told The Washington Post in 1982. “But I found that I had a tremendous mind for organizing; that was the natural thing for me. As a kid, when I wanted to play baseball, I called all the kids in the neighborhood and suddenly had a team.”

In 1947, Mr. Wein met Joyce Alexander, a Simmons College student who wrote a jazz column for the college paper and later became a medical researcher. She was African American, Mr. Wein was Jewish, and it took years to overcome both families’ objections before they were married in 1959. She died in 2005. He has no immediate surviving family members.

Mr. Wein was named a jazz master of the National Endowment for the Arts in 2005. In addition to running dozens of festivals around the world, he continued to perform as a pianist into his late 80s and appeared on more than 35 recordings.

In 2007, Mr. Wein sold his business but continued to produce the Newport festival and others. When the new company pulled out of presenting festivals in 2010, Mr. Wein stepped in to establish a nonprofit foundation to keep the Newport Jazz Festival alive in perpetuity.

Mr. Wein continued to arrange the programs for his various festivals past his 90th birthday, bringing in musicians and spectators of every age, “to destroy the myth,” he said, “that young people don’t like jazz.”