The Flonzaley Quartet was a string quartet organized in Manhattan, New York City in 1902. The group disbanded in 1929.

The quartet was the creation of Edward J. de Coppet of New York, who in 1903 engaged the original members to devote themselves entirely to quartet-playing, and not with any view to giving regular concerts in public. The group took its name from de Coppet's summer villa near Lausanne, in Switzerland, where the four musicians first rehearsed. After a long period of practice, the Quartet made a European tour and won high praise for the perfection of its ensemble and its artistic finish. Both violinists and the violist had been students of the Belgian maestro César Thomson, who would also teach members of a contemporaneous pioneering American chamber group, the Zoellner Quartet. The group was first heard in New York, in private and at charity concerts, in autumn 1904, but it did not give a public concert in the United States until 5 December 1905. After that it appeared regularly in Europe and America. The members stuck to the original principle of not accepting any outside engagement, and having no pupils, and by devoting themselves entirely to the quartet maintained a position of acknowledged superiority in their field.

In 1914 the group asked Igor Stravinsky to write them a work. This resulted in his "Three pieces for String Quartet". A few years later they also commissioned him to write "Concertino", a one-movement work. Éduard de Coppet died in 1916, and his son André continued thereafter to maintain the Quartet. The original violist Ugo Ara left the group to join the Italian army, resulting in his replacement. The Quartet performed worldwide until disbanding in 1929.

One of their final public concerts was at The Town Hall in Manhattan, New York City on March 17, 1929. They broadcast their farewell concert over station WEAF (now WFAN) on May 7, 1929.