Rebel, who had an early interest in natural history and butterflies, first became a lawyer.

He devoted his spare time to studying Lepidoptera and established the entomological section of the Botanical and Zoological Society of Vienna.

He succeeded Alois Friedrich Rogenhofer (1831–1897) as keeper of the Lepidoptera collection of the Naturhistorisches Museum in Vienna, a post he held from 1897 to 1932.

He published more than 300 publications on Lepidoptera and a catalogue of Palearctic butterflies Otto Staudinger (1830–1900) - Catalog Lepidopteren des palaearctischen Faunengebietes.

Vladimir Nabokov (1899–1977) included Rebel as a character in his short story "The Aurelian".