He was born Robert Knauth in Halle, Germany, the son of Christoph Franz Knauth. In 1847, Christoph Knauth adopted his middle name Franz as his new surname, and his son followed suit.

He suffered in early life, as many musicians have suffered, from the hostility of his parents to a musical career. He was twenty years old when his father's animosity was conquered, and he was allowed to live in Dessau to study organ playing under Friedrich Schneider. The two years of study under that famous teacher were advantageous chiefly in making him uncommonly intimate with the works of Bach and Händel, his knowledge of which be showed in his editions of the St Matthew Passion, Magnificat, ten cantatas, and of Messiah and L'Allegro, though some of these editions have long been a subject of controversy among musicians.

In 1843 he published his first book of songs, which ultimately was followed by some fifty more books, containing in all about 250 songs. At Halle, Franz filled various public offices, including those of organist to the city, conductor of the Singakademie and of the Symphony concerts, and he was also a royal music-director and master of the music at the university. The first book of songs was warmly praised by Liszt and Schumann, the latter of whom wrote a lengthy review of it in Schumann's paper, Neue Zeitschrift für Musik, which later was published separately.

Deafness had begun to make itself apparent as early as 1841, and Franz suffered also from a nervous disorder, which in 1868 compelled him to resign his offices. His future was then provided for by Franz Liszt, Joseph Joachim and others, who gave him the receipts of a concert tour, amounting to some 100,000 marks.

In 1878 or 1879, he made an extensive search for Bach manuscripts in various towns, villages, and country houses in Germany. Eventually he discovered a park surrounding Schloss Witzthun where the young trees were being protected from their supporting poles by paper instead of the more normal cloth or leather. Upon examination, the paper turned out to be Bach manuscripts. After questioning the gardener, Franz found a trunk of Bach manuscripts, including many violin sonatas.[1]

In addition to songs he wrote a setting for double choir of the 117th Psalm, and a four-part Kyrie; he also edited Emanuele d'Astorga's Stabat Mater and Francesco Durante's Magnificat. He also transcribed Schubert's String Quartet in D minor "Death and the Maiden" for piano duet (1878), and made arrangements of Mozart's Quintets in C minor and C major.

He died in Dessau.