Berg had little formal music education before he became a student of Arnold Schoenberg in October 1904. With Schoenberg he studied counterpoint, music theory, and harmony. By 1906, he was studying music full-time; by 1907, he began composition lessons. His student compositions included five drafts for piano sonatas. He also wrote songs, including his Seven Early Songs (Sieben Frühe Lieder), three of which were Berg's first publicly performed work in a concert that featured the music of Schoenberg's pupils in Vienna that year. The early sonata sketches eventually culminated in Berg's Piano Sonata (Op. 1) (1907 – 1908); it is one of the most formidable "first" works ever written. Berg studied with Schoenberg for six years until 1911. Berg admired him as a composer and mentor, and they remained close lifelong friends. Berg may have seen the older composer as a father figure, as Berg's father had died when he was only 15.

Among Schoenberg's teaching was the idea that the unity of a musical composition depends upon all its aspects being derived from a single basic idea; this idea was later known as developing variation. Berg passed this on to his students, one of whom, Theodor Adorno, stated: "The main principle he conveyed was that of variation: everything was supposed to develop out of something else and yet be intrinsically different". The Piano Sonata is an example — the whole composition is derived from the work's opening quartal gesture and its opening phrase.

Berg was a part of Vienna's cultural elite during the heady fin de siècle period. His circle included the musicians Alexander von Zemlinsky and Franz Schreker, the painter Gustav Klimt, the writer and satirist Karl Kraus, the architect Adolf Loos, and the poet Peter Altenberg. In 1906, Berg met the singer Helene Nahowski, daughter of a wealthy family (said by some to be in fact the illegitimate daughter of Emperor Franz Joseph I of Austria from his liaison with Anna Nahowski); despite the outward hostility of her family, the two were married on May 3, 1911.

In 1913, two of Berg's Five Songs on Picture Postcard Texts by Peter Altenberg (1912) were premièred in Vienna, conducted by Schoenberg. Settings of aphoristic poetic utterances, the songs are accompanied by a very large orchestra. The performance caused a riot, and had to be halted. This was a crippling blow to Berg's self-confidence: he effectively withdrew the work, which is surely one of the most extraordinarily innovative and assured first orchestral compositions in the literature, and it was not performed in full until 1952. The full score remained unpublished until 1966.

From 1915 to 1918, Berg served in the Austrian Army and during a period of leave in 1917 he accelerated work on his first opera, Wozzeck. After the end of World War I, he settled again in Vienna where he taught private pupils. He also helped Schoenberg run his Society for Private Musical Performances, which sought to create the ideal environment for the exploration and appreciation of unfamiliar new music by means of open rehearsals, repeat performances, and the exclusion of professional critics.

Three excerpts from Wozzeck were performed in 1924, and this brought Berg his first public success. The opera, which Berg completed in 1922, was first performed on December 14, 1925, when Erich Kleiber directed the first performance in Berlin. Today Wozzeck is seen as one of the century's most important works. Berg completed the orchestration of only the first two acts of his later three-act opera Lulu, before he died. The first two acts were successfully premièred in Zürich in 1937, but for personal reasons Helene Berg subsequently imposed a ban on any attempt to "complete" the final act, which Berg had in fact completed in particell format. An orchestration was therefore commissioned in secret from Friedrich Cerha and premièred in Paris (under Pierre Boulez) only in 1979, soon after Helene Berg's own death. The complete opera has rapidly entered the repertoire as one of the landmarks of contemporary music and, like Wozzeck, remains a consistent audience draw.

Berg had interrupted the orchestration of "Lulu" because of an unexpected (and financially much-needed) commission from the Russian/American violinist Louis Krasner for a Violin Concerto (1935). This profoundly elegiac work, composed at unaccustomed speed and posthumously premièred, has become Berg's best-known and beloved composition. Like much of his mature work, it employs an idiosyncratic adaptation of Schoenberg's twelve tone technique that enables the composer to produce passages openly evoking tonality, including quotations from historical tonal music, such as a Bach chorale and a Carinthian folk song. The Violin Concerto was dedicated "to the memory of an Angel," Manon, the deceased daughter of architect Walter Gropius and Alma Mahler.

Other well-known Berg compositions include the Lyric Suite (1926), which was later shown to employ elaborate cyphers to document a secret love affair; the extraordinarily elaborate post-Mahlerian Three Pieces for Orchestra (completed in 1915 but not performed until after "Wozzeck"); and the Chamber Concerto for violin, piano and 13 wind instruments (1923 - 25): this latter is written so conscientiously that Pierre Boulez has called it "Berg's strictest composition" and it, too, is permeated by cyphers and posthumously disclosed hidden programs.

Berg died in Vienna, on Christmas Eve 1935, from blood poisoning apparently caused by an insect-sting induced carbuncle on his back. He had been reduced to near-poverty due to Nazi persecution and blacklisting of all Modernist music, and it is said that to save money his wife performed an ill-advised home surgery using a pair of scissors. Later he was rushed to hospital, but too late to prevent the onset of blood poisoning. He was 50 years old.

Berg is remembered as one of the most important composers of the Twentieth Century and to date is the most widely performed opera composer among the Second Viennese School. His popularity has been more easily secured than many other Modernists since he plausibly combined both Romantic and Expressionist idioms. Though Berg's Romanticism at one time seemed a drawback for some more Modernist composers, the Berg scholar Douglas Jarman writes in the New Grove: "As the 20th century closed, the 'backward-looking' Berg suddenly came as Perle remarked, to look like its most forward-looking composer."