Born in Leipzig, Backhaus studied at the conservatoire in Leipzig with Alois Reckendorf until 1899, later taking private lessons with Eugen d'Albert in Frankfurt am Main. He made his first concert tour at the age of sixteen. In 1905 he won the Anton Rubinstein Competition with Béla Bartók taking second place. He toured widely throughout his life - in 1921 he gave seventeen concerts in Buenos Aires in less than three weeks. Backhaus made his U.S. debut on January 5, 1912, as soloist in Beethoven's 5th Piano Concerto with Walter Damrosch and the New York Symphony Orchestra. In 1930 he moved to Lugano and became a citizen of Switzerland. He died in Villach in Austria where he was to play in a concert.
Backhaus was particularly well known for his interpretations of Ludwig van Beethoven and romantic music such as that by Johannes Brahms. He was also much admired as a chamber musician.