The renowned German conductor Otto Klemperer emigrated to the United States in April 1933 and became the Los Angeles Philharmonic's music director later that year. He and composers Igor Stravinsky and Arnold Schoenberg were among many great European artists who escaped pre-World War II conditions in their homelands, settled in Southern California and collaborated with the Philharmonic at Hollywood Bowl. In fact, Schoenberg wrote Fanfare for a Bowl Concert especially for the Bowl.

On September 8, 1937, the Bowl hosted a memorial concert for George Gershwin, who had died two months earlier. The nationally broadcast event reflected Gershwin's contributions to the worlds of classical music, stage and screen with appearances by conductors Otto Klemperer, Charles Previn, Nathaniel Shilkret and Alexander Steinert; Jose Iturbi as both conductor and pianist; pianist Oscar Levant, singers Lily Pons and Gladys Swarthout; movie stars Fred Astaire, Al Jolson and Edward G. Robinson; and Anne Brown and Todd Duncan from the original cast of Porgy and Bess.

Musicologist Nicolas Slonimsky claimed he was fired after conducting two weeks of concerts in 1933 because the music was too dissonant and unusual. His programs, which mixed Mozart and Strauss with such daunting contemporary works as Varese's Ionisation, undoubtedly caused some audience disapproval, but they had a profound impact on composer John Cage, who attended all of them.

Among the notable debuts of the decade were violinist Jascha Heifetz; pianists Jose Iturbi and Josef Lhevinne; singers Nelson Eddy, Kirsten Flagstad, Roland Hayes, Lotte Lehmann, Loritz Melchior, Grace Moore, Paul Robeson, John Charles Thomas; and a precocious nine-year-old conductor, Lorin Maazel.

Sergei Rachmaninoff performed his own Piano Concerto No. 2 at the Hollywood Bowl in July of 1942. Several weeks later, Vladimir Horowitz played the same composer's Piano Concerto No. 3 under the direction of William Steinberg, a performance Rachmaninoff is said to have called "the greatest moment of my life."

Although security considerations during the World War II years caused Bowl attendance to be limited at times to as few as 5,000, the music was as vital as ever. Hollywood Bowl manager Florence Irish worked with the U. S. Army to assure that programs could continue, and requested that restrictions on audience size be increased to 10,000 because the music was so important to the morale of the public and visiting soldiers and sailors. Beginning in 1944, Bowl concerts were broadcast over the Armed Forces Radio Service.

The influx of renowned European artists to the West coast continued: Igor Stravinsky conducted his own Firebird; pianists Claudio Arrau, Artur Rubinstein, violinists Yehudi Menuhin and Isaac Stern and cellist Gregor Piatigorsky were just a few of the distinguished artists to perform at Hollywood Bowl. Baritone George London, who had previously worked as an usher, made his professional debut on the Bowl stage.

Leopold Stokowski conducted the opening of the 1942 season, beginning a close relationship with the Bowl which culminated in his appointment in 1946 as music director. In 1945 he founded the "Hollywood Bowl Symphony" – essentially the Los Angeles Philharmonic re-named to reflect its world-famous summer "home." Although the orchestra resumed its original identity after only two years, Stokowski's influence was long-lasting. His use of an electronic sound system to improve acoustics was one of the first experiments in sound amplification at Hollywood Bowl.

Alfred Wallenstein, appointed Los Angeles Philharmonic Music Director in 1943, led numerous Bowl concerts. Leonard Bernstein first appeared in 1944. In 1948, Eugene Ormandy presided over the West Coast premiere of Mahler's monumental Symphony No. 8. Two notable conducting debuts were those of Serge Koussevitzky, who made his first West Coast appearances at age 75, and Andre Previn, at age 19.

Financial crisis, capped by a costly and unpopular opening production of Strauss' opera, Die Fledermaus, brought the 1951 season to an abrupt close. In their now-legendary campaign to save Hollywood Bowl, Dorothy Buffum Chandler and her "Emergency Committee" turned the situation from bankruptcy to a revitalized artistic and community vision for the Bowl. The season actually closed with a small profit, and financial support for the amphitheatre allowed for modernization of the physical plant and enhancement to the grounds beginning in 1952.

New to the Bowl stage in the 1950s were conductors Sir Adrian Boult, Philharmonic music director Eduard van Beinum (1956-1959), Herbert von Karajan and Georg Solti; while Sir William Walton, Igor Stravinsky and Heitor Villa-Lobos were among the distinguished composers who conducted the orchestra in their own works. Carmen Dragon and Andre Kostelanetz brought lighter classical programming to the schedule. Otto Klemperer led the 1000th concert at the Bowl on September 3, 1953 – a performance of Beethoven's Ninth Symphony. Stellar soloists of the era included singers Marilyn Horne, Leontyne Price and Elisabeth Schwarzkopf; pianists Van Cliburn, Walter Gieseking and Rudolf Serkin. Leonard Bernstein served as music director for an ambitious five-night "Festival of the Americas" in 1955.

Two long-term relationships began in the 1960s that strongly influenced the way the Hollywood Bowl would develop in future years. Zubin Mehta, music director of the Los Angeles Philharmonic from 1962–1978, first appeared at the Hollywood Bowl in 1961, and at the end of the decade, Ernest Fleischmann was hired as general director of the Hollywood Bowl and executive director of the Los Angeles Philharmonic. Mehta's enormous popularity and spirited enthusiasm complemented Fleischmann's keen administrative skills and innovative concepts regarding musical performance. One of the most visible and popular of Fleichmannn's innovations – music with fireworks – made its debut at the 1969 Tchaikovsky Spectacular. Although all-Tchaikovsky concerts ending with the 1812 Overture had been programmed in the past, the added element of fireworks synchronized to the music was a brilliant new addition. Mehta conducted, the audience loved it, and a Bowl tradition was born.

In 1962 Stravinsky celebrated his 80th birthday at the Bowl, at a concert in which he shared conducting duties with Robert Craft. That same year Andre Kostelanetz conducted Tchaikovsky in the first nationally telecast Bowl concert. Opera stars Birgit Nilsson, Beverly Sills and Joan Sutherland were among the decade's high-profile guest artists, as were pianists Victor Borge, Alicia de Larrocha and Andre Watts. Cellist Jacqueline Du Pré appeared on a program conducted by her husband, Daniel Barenboim. Twenty-one year old violinist Itzhak Perlman – not yet a superstar – made his Bowl debut in 1966. First-time conductors included Vladimir Ashkenazy, Eugen Jochum, Rafael Kubelik and Seiji Ozawa. The New York Philharmonic paid a visit to the Bowl with Leonard Bernstein conducting.

The 1970s were the decade of "marathon" concerts at Hollywood Bowl. Bowl manager Ernest Fleischmann adapted rock concert techniques to attract younger and more diverse audiences to classical programs. These six-hour (or longer) events focused on particular themes or composers (Baroque, Beethoven, Stravinsky), featured performances by the Philharmonic and numerous smaller ensembles, were affordably priced, offered unreserved seating and an invitation to audience members "come and go as you like." Soprano Kathleen Battle made her Bowl debut in a Mozart Marathon. The Bowl's "50th Birthday Superseason" – 1972 – opened auspiciously with soprano Jessye Norman making her U.S. debut in a concert performance of Aida conducted by James Levine. Flutist James Galway and conductor Simon Rattle also made their American debuts at the Bowl during the seventies, and Luciano Pavarotti appeared locally for the first time in a 1973 concert performance of La Boheme. Carlo Maria Giulini, who succeeded Mehta as the Philharmonic's music director, Christopher Hogwood, Michael Tilson Thomas, Leonard Slatkin and David Zinman all made significant impact in their first Bowl conducting appearances. Virtuoso pianists Emanuel Ax and Alfred Brendel, cellists Lynn Harrell and Yo-Yo Ma and flutist Jean-Pierre Rampal became favorites with Los Angeles audiences in the seventies and have remained so in the years since.

In 1980 the Los Angeles Philharmonic-sponsored Jazz at the Bowl was introduced. The new series formalized the Bowl's increasingly broad programming approach, which also included a new Virtuoso Series of recitals by major classical artists. Leonard Bernstein and Ernest Fleischmann co-founded the Los Angeles Philharmonic Institute in 1981 to provide world-class training for young instrumentalists and conductors. Esa-Pekka Salonen, the Los Angeles Philharmonic's music director since 1992, first appeared at Hollywood Bowl in 1985, after having made his American debut with the Philharmonic the previous winter season. The decade also saw Bowl conducting debuts by Herbert Blomstedt, Myung-Whun Chung, Charles Dutoit and Yuri Temirkanov. First time solo artists included pianists Katia and Marielle Labeque, Ivo Pogorelich and Krystian Zimerman; violinists Joshua Bell and Midori; clarinetist Richard Stoltzman; and singers Kiri Te Kanawa and Frederica von Stade.

The Hollywood Bowl Orchestra was founded in 1991 as a separate entity from the Los Angeles Philharmonic, with a musical identity and personnel all its own. Its concerts reflect a wide range of repertoire. The Orchestra's conductor, John Mauceri, is a leader in the preservation of two of America's great art forms, the American musical and film music. His programs with the Hollywood Bowl Orchestra typically featured important scores composed for the stage and screen played alongside classical and operatic selections. Through their concerts and recordings, Mauceri and the Hollywood Bowl Orchestra shined the spotlight on many neglected or forgotten masterpieces that were composed right here in Southern California.

An unprecedented variety of musical styles and artists filled the Bowl in the nineties. With the Los Angeles Philharmonic under the direction of Esa-Pekka Salonen and important guest conductors, Bowl audiences continued to enjoy classical masterworks and innovative contemporary works, including Salonen's own compositions. Mauceri and the Hollywood Bowl Orchestra presented the Los Angeles premiere of Paul McCartney's symphonic poem Standing Stone, film projections on enormous screens enhanced live performances of film scores in a new type of multi-media event, and fireworks programs became more spectacular and plentiful than ever. Oscar and Grammy award-winning composer-conductors Henry Mancini and John Williams performed their own works to capacity crowds. The Bowl hosted Los Angeles Festival events under its avant-garde director Peter Sellars in 1990 and 1993, World Cup Week in 1994, and celebrated its own 75th season in 1996. At the end of the decade, the Bowl began a two-season survey of best-loved works in the classical repertoire and introduced a new series devoted to "world music," an indication of the vital role the Bowl continues to play in the cultural life of Southern California's richly diverse community.

The Bowl continued its substantial classical programming throughout the first decade of the 21st century. The U.S. debut of Venezuelan conductor Gustavo Dudamel at the age of 24 happened at the Bowl in 2005. In the fall of 2009, he became the tenth Music Director of the Los Angeles Philharmonic. His tenure was inaugurated in a festival concert at the Hollywood Bowl called "Bienvenido Gustavo!" Inspired by Dudamel's dedication to the music education of young children, the concert included performances by young people along with established artists including Andrae Crouch with a gospel choir, Flea (from the Red Hot Chili Peppers) with the Silverlake Conservatory Ensemble, Herbie Hancock with the Los Angeles County High School for the Arts Jazz Band, David Hidalgo and Taj Mahal with Los Cenzontles, and the Philharmonic sponsored YOLA–Expo Center Youth Orchestra conducted by Gustavo Dudamel himself. The concert concluded with a performance of Beethoven Symphony No. 9 with Dudamel conducting the Los Angeles Philharmonic and a combined choir from throughout the Los Angeles area.