Born in Kiev in the Ukraine, Horowitz had piano lessons from an early age, initially from his mother, who was herself a professional pianist. In 1912 he entered the Kiev Conservatory, leaving in 1919, and playing the third piano concerto of Rachmaninoff at his graduation. His first solo recital followed in 1920.
His star rapidly rose — he soon began to tour Russia (where he was often paid with bread, butter and liquor rather than money due to the country's economic hardships), and in 1926 made his first appearance outside his home country, in Berlin. He later played in Paris, London and New York City, and it was in the United States that he eventually settled in 1940. He became a United States citizen in 1944.
In 1932 he played for the first time with the conductor Arturo Toscanini in a performance of Beethoven's Piano Concerto No. 5 (the Emperor concerto). The two went on to appear together many times, both on stage and on record. In 1933, Horowitz married Wanda Toscanini, the conductor's daughter.
Despite receiving rapturous receptions at his recitals, Horowitz became increasingly unsure of his abilities as a pianist. Several times he withdrew from public performances, and it is said that on several occasions, the only thing that stopped him from cancelling recitals at the last moment was the persuasiveness of his wife. After 1970 he gave solo recitals only rarely.
Horowitz made many recordings, starting in 1928 upon his arrival in the United States and ending right before his death in 1989. His early recordings were made for EMI, the most notable of which is his 1930 recording of Rachmaninoff's Piano Concerto No. 3 with Albert Coates and the London Symphony Orchestra, the first known recording of that piece. In the 1940s and 1950s, Horowitz recorded for RCA Victor. During this period, he made his first recording of the Tchaikovsky Piano Concerto No. 1. After 1953, when Horowitz went into retirement, he made a number of acclaimed recordings at home, including discs of Alexander Scriabin and Muzio Clementi.
In 1962, Horowitz began recording for Columbia Records, and it is these recording which are his most famous. The most famous among them is his 1965 return concert at Carnegie Hall and his 1968 performance from his television special, Horowitz on TV, featuring Scriabin's D# minor Etude, Op.8, No.12 and Horowitz's own Variations on a Theme from Bizet's Carmen, the most famous of his piano transcriptions along with the Stars and Stripes Forever. From 1965 until 1982, all of Horowitz's recordings were done live.
After another brief retirement from 1982 until 1985, Horowitz returned to recording and occasional concertizing. In 1986, Horowitz made a return to the Soviet Union to give a series of concerts in Moscow and Leningrad. In the new atmosphere of communication and understanding between the USSR and the USA, these concerts were seen as events of some political, as well as musical, significance. The concert was recorded and released, entitled "Horowitz in Moscow".
Horowitz died in New York of a heart attack. He was buried in the Toscanini family tomb in Cimitero Monumentale, Milan, Italy. His body was rumored to have been buried along with a book Hanon's piano excercises, because according to Horowitz, "I never want to do anything without warming up; that includes dying."
Horowitz is best known for his performances of the romantic repertoire, with his six recordings of Rachmaninoff's Piano Concerto No. 3 and Franz Liszt's Hungarian Rhapsodies being particularly highly acclaimed. Other well-known recordings include works by Schumann, Scriabin, Chopin and Schubert. He was sometimes accused of self indulgence in his performances, but his extravagances were always well received by his audiences. He had an unusual technique, playing with very straight fingers. He did much to champion contemporary Russian music, giving the American premieres of Sergei Prokofiev's 6th, 7th and 8th piano sonatas.