In 1875, the Cheney family moved to Chelsea, a suburb just across the Mystic River from Boston. They were advised there to enroll Amy in a European conservatory, but opted instead for local training, hiring Ernst Perabo and later Carl Baermann (himself a student of Franz Liszt) as piano teachers. In 1881–82, fourteen-year-old Amy also studied harmony and counterpoint with Junius W. Hill. This would be her only formal instruction as a Composer, but "[s]he collected every book she could find on theory, composition, and orchestration ... she taught herself ... counterpoint, harmony, fugue," even translating Gevaert's and Berlioz's French treatises on orchestration, considered "most composers' bibles," into English for herself.

Amy Cheney made her concert debut at age sixteen on October 18, 1883 in a "Promenade Concert" conducted by Adolph Neuendorff at Boston's Music Hall, where she played Chopin's Rondo in E-flat and was piano soloist in Moscheles's piano concerto No. 3 in G minor, to general acclaim: as biographer Fried Block comments, "[i]t is hard to imagine a more positive critical reaction to a debut," and her audience was "enthusiastic in the extreme." The next two years of her career included performances in Chickering Hall, and she starred in the final performance of the Boston Symphony's 1884–85 season.

Amy was married the same year (1885) to Dr. Henry Harris Aubrey Beach, a Boston surgeon twenty-four years her senior (she was eighteen at the time). Her name would subsequently be listed on concert programs and published compositions as "Mrs. H. H. A. Beach." The marriage was conditioned upon her willingness "to live according to his status, that is, function as a society matron and patron of the arts. She agreed never to teach piano, an activity widely associated with women" and regarded as providing "pin money." She further agreed to limit performances to two public recitals per year, with profits donated to charity, and to devote herself more to composition than to performance (although, as she wrote, "I thought I was a Pianist first and foremost.") Her self-guided education in composition was also necessitated by Dr. Beach, who disapproved of his wife studying with a tutor. Restrictions like these were typical for middle- and upper-class women of the time: as it was explained to a European counterpart, Fanny Mendelssohn, "Music will perhaps become his [Fanny's brother Felix Mendelssohn's] profession, while for you it can and must be only an ornament.".

In the early 1890s, Beach started to become interested in folk songs. She shared that interest with several of her colleagues, and this interest soon came to be the first nationalist movement in American music. Beach's contributions included about thirty songs inspired by folk music, including Scottish, Irish, Balkan, African-American, and Native American origins.

Sacred choral works among Beach's compositions are mainly for 4 voices and organ, but a few are for voices and orchestra, two being the Mass in E-flat major (1892) and her setting of St. Francis's Canticle of the Sun (1924, 1928), first performed at St. Bartholomew's in New York. A setting of the Te Deum with organ was first performed by the choir of men and boys at Emmanuel Episcopal Church in Boston. The Capitol Hill Choral Society of Washington, D.C., recorded the Canticle of the Sun, seven Communion Responses, and other pieces by Beach in 1998, led by its Musical Director Betty Buchanan, who founded the Society in 1983.

She wrote the Gaelic Symphony (1896) and the Piano Concerto in C-sharp minor. Another orchestral piece, Bal masque, has a solo piano version. Two further pieces, Eilende Wolken and Jephthah's Daughter, are for orchestra with voice.

In January 1897 Amy played, with Franz Kneisel, in the premiere of her Sonata for Piano and Violin, which she had composed in the spring of 1896. Critical reception In New York was mixed, but in Europe it was better: Composer and Pianist Teresa Carreño performed the piece with Violinist Carl Halir in Berlin, October 1899 and wrote to Amy:

In 1900, with the Kneisel Quartet, Amy performed the Brahms quintet for Piano and Strings. Beach wrote her own Quintet for piano and strings, in F-sharp minor, in 1905. "During Beach's lifetime, the work had well over forty performances, in dozens of cities, over the radio, and by many string quartets. A large number of those performances were with the Composer at the piano, most notably during a lengthy tour in 1916 and 1917 with the Kneisel Quartet." This was the 33rd and last season for the Quartet. Amy performed her Quintet with them in Boston, Brooklyn, Chicago, and Philadelphia.

Variations on Balkan Themes, Beach's "longest and most important solo" piano work, was composed in 1904. It responded to revolts in the Balkans against the then ruling Ottoman Empire.

Her husband died in June 1910 (the couple had been childless) and her mother 7 months later. Her father, Charles Cheney, had died in 1895. Beach felt unable to work for a while. She went to Europe in hopes of recovering there. In Europe she changed her name to "Amy Beach". She travelled together with Marcella (Marcia) Craft, an American Soprano who was "prima donna of the Berlin Royal Opera." Beach's first year in Europe "was of almost entire rest." In 1912 she gradually resumed giving concerts, Her European debut was in Dresden, October 1912, playing her violin and piano sonata with Violinist "Dr. Bülau," to favorable reviews. In Munich in January 1913, she gave a concert, again with her violin sonata, but now with three sets of songs, two of her own and one by Brahms, and solo piano music by Bach, Beethoven, and Brahms. Two critics were rather unfavorable, one calling Beach's songs "kitschy." She was unfazed, saying the audience was "large and very enthusiastic." Demand arose for sheet music of Beach's songs and solo piano pieces, beyond the supply that Beach's publisher Arthur P. Schmidt had available for German music stores. Later In January, still in Munich, she performed in her Piano Quintet; a critic praised her composing, which he did not like all that well, more than her playing. In a further concert in Breslau, only three of Beach's songs were on the program, fewer than in Munich.

While continuing to get income from her compositions published by Arthur P. Schmidt, during 1914–1921 she had new compositions published by G. Schirmer. The Centerville cottage had been built on a five-acre property Amy had bought with royalties from one song, Ecstasy, 1892, her most successful up until then.

In 1915, the Panama Pacific International Exposition in San Francisco commemorated the opening of the Panama Canal and the city's recovery from the 1906 earthquake and fire. Amy Beach was honored often by concerts of her music and receptions during 1915, and her Panama Hymn was commissioned for the occasion. In 1915 and again in 1916 Amy in San Francisco visited her aunt Franc and cousin Ethel, who by then were her closest living relatives. About August 6, 1916, Amy, Franc, and Ethel left San Francisco together, leaving Franc's husband Lyman behind, a "fifty-year-old marriage broken apart", for unknown reasons. The three women took up residence in Hillsborough, New Hampshire, where Franc and Amy's mother had been born. Lyman "was settled" in a Veterans' Home in California from 1917 until his death in 1922. After 1916, "Hillsborough was Beach's official residence: there she voted in presidential elections." In 1918, Amy's cousin Ethel "developed a terminal illness," and Amy spent time taking care of her, as Franc, at age 75, "could hardly" do so by herself.

Franz Kneisel was a leading Violinist in Boston and beyond, having been hired at about age 20 by Wilhelm Gericke, Conductor of the Boston Symphony Orchestra, as concertmaster of the orchestra. Soon after arriving in Boston, he formed the Kneisel String Quartet with three other string players of the Boston Symphony. (The Quartet lasted until 1917. Meantime Kneisel moved to New York in 1905.) In 1894 Amy had joined the Quartet in performing Robert Schumann's Quintet for piano and strings.

Aside from concert tours and the time of Ethel's illness until her death in 1920, Beach also spent part of her time in New York. Someone had asked her if she were the daughter of Mrs. H. H. A. Beach. She resumed using that married name, but used "Amy Beach" on bookplates and stationery. For a few summers she composed at her cottage in Centerville, Massachusetts on Cape Cod.

From 1921 on she spent part of each summer as a Fellow at the MacDowell Colony in Peterborough, New Hampshire, where she composed several works and encountered other women composers and/or Musicians, including Emilie Frances Bauer, Marion Bauer, Mabel Wheeler Daniels, Fannie Charles Dillon, and Ethel Glenn Hier, who "were or became long-time friends" of Beach. But there were "generational and gender divisions" among the Fellows in music, with some feeling that Beach's music was "no longer fashionable".

In 1924 Beach sold the house in Boston she had inherited from her husband. Her aunt Franc had become "feeble" around 1920, developed dementia in 1924, and died in November 1925 in Hillsborough, after which Beach had no surviving relatives as close as Ethel and Franc had been. In the fall of 1930 Beach rented a studio apartment in New York. There she became the virtual composer-in-residence at St. Bartholomew's Episcopal Church. Her music had been used during the previous 20 years in services at the church, attributed to "H. H. A. Beach", with "Mrs." added only from 1931 on.

Beach spent the winter and spring of 1928–29 in Rome. She went to concerts "almost daily" and found Respighi's Feste Romane, just written in 1928, to be "superbly brilliant," but disliked a piece by Paul Hindemith. In March 1929 she gave a concert to benefit the American Hospital in Rome, in which her song "The Year's at the Spring" was encored and a "large sum of money" was raised. Beach, like her friends in Rome, briefly became an admirer of the Italian dictator Mussolini. She returned to the United States with a two-week stopover in Leipzig, where she met her old friend, the singer Marcella Craft.

She was a member of Chapter R (New York City) of the P.E.O. Sisterhood. Late in her life, she colloborated on the "Ballad of P.E.O." with the words written by Ruth Comfort Mitchell, Chapter BZ/California. Heart disease led to Beach's retirement in 1940 and her death in New York City in 1944. Amy Beach is buried with her husband in the Forest Hills Cemetery in the Jamaica Plain neighborhood of Boston, Massachusetts.

Despite her fame and recognition during her lifetime, Beach was largely neglected after her death in 1944 until the late 20th century. Efforts to revive interest in Beach's works have been largely successful during the last few decades.

Beach's Piano Concerto has been praised as an overlooked masterwork by modern critics. In 1994 Phil Greenfield of The Baltimore Sun called it "a colorful, dashing work that might become extremely popular if enough people get a chance to hear it. In 2000 Joshua Kosman of the San Francisco Chronicle also lauded the composition, writing:

The symphony has received praise from modern critics, such as Andrew Achenbach of Gramophone, who in 2003 lauded the work for its "big heart, irresistible charm and confident progress." In 2016, Jonathan Blumhofer of The Arts Fuse wrote:

Beach was a musical intellectual who wrote for journals, newspapers, and other publications. She gave advice to young Musicians and composers – especially female composers. From career to piano technique advice, Beach readily provided her opinions in articles such as, "To the Girl who Wants to Compose", and "Emotion Versus Intellect in Music." In 1915, she had written Music’s Ten Commandments as Given for Young Composers, which expressed many of her self-teaching principles.

In 1994, the Boston Women's Heritage Trail placed a bronze plaque at her Boston address, and in 1995, Beach's gravesite at Forest Hills Cemetery was dedicated. In 1999, she was put into the American Classical Music Hall of Fame and Museum in Cincinnati, Ohio. In 2000, the Boston Pops paid tribute by adding her name as the first woman joining 86 other composers on the granite wall of Boston's famous Hatch Shell. In honor of Beach's 150th birthday, Marty Walsh (politician), Mayor of the City of Boston, declared September 5, 2017, "Amy Beach Day." "I, Martin J. Walsh, Mayor of Boston, do hereby declare September 5, 2017 to be: Amy Beach Day in the City of Boston. I urge all my fellow Bostonians to join me in recognizing and honoring Amy Beach as one of the most successful American composers." The New York Times commemorated Beach's sesquicentennial with an article, "Amy Beach, a Pioneering American Composer, Turns 150" by william Robin.