André Watts, a pianist whose mighty technique and magnetic charm awed audiences and made him one of the first Black superstars in classical music, died on Wednesday at his home in Bloomington, Ind. He was 77.

The cause was prostate cancer, said his wife, Joan Brand Watts.

Mr. Watts was an old-world virtuoso — his idol was the composer and showman Franz Liszt — with a knack for electricity and emotion. He sometimes hummed, stomped his feet and bobbed his head while he played, and some critics faulted him for excess. But his charisma and his technical powers were unquestioned, which helped fuel his rise to the world’s top concert halls.

“My greatest satisfaction is performing,” Mr. Watts told The New York Times in 1971, when he was 25. “The ego is a big part of it, but far from all. Performing is my way of being part of humanity — of sharing.”

“There’s something beautiful,” he added, “about having an entire audience hanging on a single note.”

Mr. Watts, whose father was Black and whose mother was white, was a rarity in a field where musicians of color have long been underrepresented. While he preferred not to speak about race, he was celebrated as a pioneer who defied stereotypes about classical music and helped open doors for aspiring artists of color.

His own arrival in the spotlight was auspicious. In 1963, when he was 16, he won an audition to appear with Leonard Bernstein and the New York Philharmonic as part of the maestro’s nationally televised series of Young People’s Concerts.

Mr. Bernstein was effusive as he introduced the young pianist to the crowd at Philharmonic Hall. “He sat down at the piano and tore into the opening bars of a Liszt concerto in such a way that we simply flipped,” Mr. Bernstein said, recounting the young pianist’s audition.

Mr. Watts was then living in relative obscurity in Philadelphia, practicing on a beat-up piano with 26 missing strings. But he emerged from his performance of Liszt’s Piano Concerto No. 1 a bona fide star.

A couple weeks later, Mr. Bernstein invited him to make his formal Philharmonic debut, substituting for the eminent pianist Glenn Gould. He later credited Mr. Bernstein with handing him a career “out of thin air.”

“It was like being God Almighty at 16,” he told The Times.

André Watts was born on June 20, 1946, in Nuremberg, Germany, the son of Herman Watts, a noncommissioned officer stationed overseas for the U.S. Army, and Maria (Gusmits) Watts, an amateur pianist from Hungary.

His mother, who was fond of playing Strauss waltzes on the family’s Blüthner piano, encouraged André’s musical studies, and as a 6-year-old he took up the piano after a flirtation with the violin.

“I liked the sound,” he recalled in a 1993 television appearance. “I would hold the pedal down for pages and pages of music and just let this mushroom sound go.”

When he was 8, the family moved to the United States for his father’s work, ultimately settling in Philadelphia. But his parents’ relationship grew strained, and they divorced when he was 13. He rarely saw his father in the following decades.

His mother, who worked as a receptionist at an art gallery to help pay for his piano lessons, became a dominant influence. When he was young, she served as teacher, coach and manager, and she enforced a strict practice regimen.

André struggled to fit in at school, quarreling with teachers and classmates (he taught himself judo to deter bullies). He sometimes felt isolated, he recalled in interviews, because he identified as neither Black nor white.

When he went to Florida as a teenager to perform, his manager, invoking the state’s history of discrimination against interracial couples, warned that he could be viewed suspiciously.

But his mother told him that he should not blame racism for his troubles. “If someone is not nice to you,” Mr. Watts recalled her saying when he was interviewed by The Christian Science Monitor in 1982, “it doesn’t have to be automatically because of your color.”

“These kinds of advice have taught me that when I’m in a complex personal situation, I don’t have to conclude it is a racial thing,” he said. “The more subtle things in interpersonal exchange are, first of all, never provable as racist anyway. So it’s a waste of time.”

He later credited Mr. Bernstein with helping him gain acceptance in the classical music industry, which had long been seen as the dominion of the white and wealthy. In introducing Mr. Watts at the Young People’s Concert, Mr. Bernstein described his international heritage and said, “I love that kind of story.”

In 1964, the year after his debut with Mr. Bernstein, Mr. Watts won a Grammy Award for most promising new classical recording artist. Despite his early success, he tried to remain grounded, adopting a motto, “Even this shall pass away,” taken from a poem by the 19th-century poet and abolitionist Theodore Tilton. (His mother had the phrase inscribed on a gold medallion that he wore around his neck.)

He graduated in 1972 from the Peabody Institute at Johns Hopkins University in Baltimore, where he studied with the pedagogue and performer Leon Fleisher. He was already a regular on the global concert circuit by the time he graduated, playing the Liszt concerto for which he was known, as well as works by Chopin, Franck, Saint-Saëns and others, before sold-out crowds in Boston, Los Angeles, London and elsewhere.

Mr. Watts earned mixed reviews early in his career; critics said that while he had flair and confidence, he could sometimes get carried away. But they agreed that he possessed a special ability to communicate from the keyboard.

“He has that kind of personal magic that makes an Event of a concert, and Philharmonic Hall had the electric feeling that occurs only when an important artist is at work,” Harold C. Schonberg of The New York Times wrote in 1970. “It cannot be taught, this mysterious transmission from stage to audience, and Mr. Watts has it in very large measure.”

While Mr. Watts thrived on the stage, recording was more of a challenge; he said he was prone to clam up without an audience. And at times he suffered financial and management difficulties, including in 1992, when he was ordered by a New York State appellate court to pay Columbia Artists Management nearly $300,000 in disputed commissions.

But he maintained his popularity, performing at White House state dinners, making frequent appearances on television and becoming one of classical music’s most bankable stars. His success brought new luxuries and curiosities. He grew fond of Montecristo cigars, fine wines and caviar, and he began to study Zen Buddhism.

In 1987, Mr. Watts was featured in an episode of “Mister Rogers’ Neighborhood” about learning from mistakes.

“When I’m feeling unhappy,” he said on the program, “going to the piano and just playing gently and listening to sounds makes everything slowly seem all right.”

His collaborators described him as a musician of preternatural talent who was always looking to improve. The conductor Robert Spano said that Mr. Watts never performed a piece the same way twice, intent on finding fresh meaning each time.

“Every night was a new adventure,” Mr. Spano said. “He radiated love to people and to the music, and it was unmistakable. That’s why he was so loved as a performer, because of the generosity of his music making.”

He was also a role model for many Black musicians. The conductor Thomas Wilkins, a colleague of Mr. Watts’s at Indiana University, where Mr. Watts had taught since 2004, recalled him as a devoted teacher who was eager to “hand down this ferociousness about trying to become better.”

“Whenever we were onstage together, there was this unspoken acknowledgment that we were in a world where a lot of people think we shouldn’t be,” said Mr. Wilkins, who is Black. “It was an affirmation.”

In addition to his wife, Mr. Watts is survived by a stepson, William Dalton; a stepdaughter, Amanda Rees; and seven step-grandchildren.

At the start of the pandemic in 2020, Mr. Watts, who was diagnosed with Stage 4 prostate cancer in 2016, had been planning a feat: He would play Ravel’s Piano Concerto for the Left Hand in a version that he had reworked for the right hand (his left was recovering from a nerve injury). As he practiced on his twin Yamaha pianos, he got daily inspiration from a one-legged starling that emerged outside his home in Bloomington.

Ultimately, Mr. Watts was unable to perform the concerto because of health problems and the pandemic. He mostly stopped playing the piano after the concerts were canceled, instead spending time with students.

His wife said that music had sustained him throughout his life, beginning with his demanding childhood and through his health struggles.

“Music was how he endured and how he survived,” she said. “When he actually played, then he was happy. It just really lifted up his soul.”

He described music as a sacred space in which he felt he could breathe and flourish.

“Your relationship with your music is the most important thing that you have, and it is, in the sense of private and sacred, something that you need to protect,” he said before a concert in Baltimore in 2012. “The dross of everyday life is very, very powerful and very strong. So you need to protect your special relationship with your music.”

Kirsten Noyes contributed research.