Born Belle Miriam Silverman on May 25, 1929 in Brooklyn, she was already singing in public by age 3 and was performing professionally on radio, as "Bubbles" Silverman, by age 4. At age 7 she adopted the stage name Beverly Sills; she was a winner on the radio show Major Bowes' Amateur Hour and subsequently joined the cast of Bowes's Capitol Family Hour, on which she sang opera arias and tap-danced. At that time she began voice lessons with Estelle Liebling, her lifelong teacher and coach.

At age 12 — by which time she had memorized all the arias on her mother's records of the legendary soprano Amelita Galli-Curci — her father had her abandon performing and concentrate in earnest on her schoolwork, her vocal study with Liebling and piano lessons with Paolo Gallico. She was a natural performer, by the time she reached high school, at and the Professional Children's School in Manhattan, she was again appearing regularly on stage and radio.

Her early vaudeville-like appearances militated against making a career in opera, but she persevered. She began singing operetta professionally at about age 16 and made her operatic debut when she was 18, playing Frasquita in a Philadelphia Civic Opera production of Carmen. In her early 20s Sills toured the U.S. and Canada with the Charles Wagner Opera Company; she made her San Francisco opera debut in 1953 as Helen of Troy in Boito's Mefistofele and sang Donna Elvira in Don Giovanni there the same season. And she tried repeatedly to get accepted into New York City Opera's company. In a 1980 interview, she recalled singing for City Opera's music director, Joseph Rosenstock: "I had auditioned so many times for him I was angry. When he asked me what I was going to sing, I told him he had heard my entire soprano repertoire, so I was going to sing mezzo-soprano roles today."

Sills finally appeared with City Opera in 1955 as Rosalinde in Die Fledermaus. She gradually became a star with the company and in 1958 created the title role in Douglas Moore's The Ballad of Baby Doe.

In 1956 Sills married financial journalist Peter Greenough, a member of the family who owned the Cleveland Plain Dealer. When he took a job at The Boston Globe, the couple moved to Massachusetts, where Sills would sing many roles with Sarah Caldwell's innovative Opera Company of Boston. Sills and Greenough had two children, Meredith in 1959 and Peter, Jr. ("Bucky") in 1961. When she learned that her daughter was profoundly hearing-impaired and her son was mentally disabled, she left the stage for a period to care for them. Later, after she had become famous, she devoted a great deal of time and effort to raising money for the March of Dimes, a charity dedicated to the battle against birth defects.

In 1966, critics from all over the world came to New York for the opening of the new Metropolitan Opera House at Lincoln Center, with the world premiere of Samuel Barber's Anthony and Cleopatra. Just across the plaza, Sills was singing another Cleopatra, in City Opera's production of Handel's Giulio Cesare, then virtually unknown. When the reviewers, unimpressed with Barber's opera, crossed Lincoln Center Plaza and heard Sills's performance, she became an international star almost overnight.

Over the next decade or so, Sills sang virtuoso roles by Rossini, Donizetti, Mozart and Bellini, as well as Gilda in Rigoletto and Violetta in La traviata, at many illustrious opera houses, including London's Covent Garden, the Teatro San Carlo in Naples, the Vienna State Opera and the Teatro Colón in Buenos Aires. Her 1969 La Scala debut as Pamira in Rossini's Siege of Corinth landed her on the cover of Newsweek magazine; two years later she was on the cover of Time, labeled "America's Queen of Opera."

Sills maintained her relationship with City Opera throughout this period, regularly taking on new roles — most famously, the three Tudor-era queens in Donizetti's Maria Stuarda, Anna Bolena and Roberto Devereux (in which she sang Elizabeth I, a role which she later said took five years off of her career.)

Yet for years she was not invited to sing at the Metropolitan Opera House (it was said that longtime general manager Rudolf Bing did not want to hire her); she finally made her debut there in 1975, again as Rossini's Pamira, when her voice was past its peak. The Met did make good use of Sills for the five years it had her, casting her as Violetta, Donizetti's Lucia, and Massenet's Thaïs and Cendrillon.

During the height of Sills's stardom in the 1970s, she appeared regularly on television talk shows and variety specials with such personalities as Mike Douglas, Dick Cavett, Dinah Shore, Carol Burnett (a good friend with whom she sang duets) and even the Muppets. She was particularly associated with Johnny Carson and his Tonight Show, even filling in for Carson as guest host on occasion. Her warm and unpretentious personality made her very popular with the general public, and she used that renown to popularize opera.

Sills gave her farewell performance on October 27, 1980 at New York City Opera, of which she had become general director the previous year. When she took over management of the company, it was $5 million in debt and seen as teetering. She restored public confidence, greatly increased fundraising (she proved gifted at charming money out of donors), led the company through the traumatic loss of most of its costume stock in a warehouse fire, made City Opera the first U.S. company to use supertitles, and generally made the company into a viable and stable enterprise. She retired as general director in 1989 and became president of City Opera's board; she stepped down from that role in 1991, crossed Lincoln Plaza and joined the Met's board of directors.

In 1994 Sills became chairman of Lincoln Center, Inc., where she was similarly successful as fundraiser and administrator, skillfully mediating between the complex's sometimes-contentious constituent companies.

Sills stepped down from the chair at Lincoln Center in 2002, saying that she was ready to retire — but within six months she was back, as chairman of the Metropolitan Opera's board. (Having said that she needed to stop and smell the proverbial roses, she explained her return thus: "So I smelled the roses and developed an allergy.") Among her most notable achievements in her three years at the Met were raising the money to save the company's Saturday afternoon radio broadcasts after longtime sponsor Chevron Texaco withdrew its support and recruiting Peter Gelb to succeed Joseph Volpe as general manager.

Sills resigned from the Met rather suddenly in January 2005, due in particular to the deteriorating health of the long-ailing Greenough, who died in September of 2006, shortly before their 50th anniversary. Sills herself continued until quite recently to make occasional public appearances, such as hosting several of the Met's new high-definition simulcasts into movie theaters this past winter and spring. A long-time friend of Barbara Walters, Sills even appeared as a guest co-host of ABC-TV's The View this past season.