Siegfried Fuchs was the son of the commercial agent Rudolf Fuchs from Deutschkreutz/Zelem and his wife Mathilde, née Grünwald. He studied law at the University of Vienna, graduating on 11 April 1908. In April 1918 he was admitted to the Vienna Rechtsanwaltskammer (bar association) and worked thereafter in his office at Mölkerbastei 3 in the 1st district. While still a student, he had begun to collect books, music manuscripts, scores, Viennensia and fashion items. He also owned musical instruments. After the annexation of Austria to the Nazi German Reich, Fuchs faced racial persecution on account of his origins. Under the Fifth Regulation to the Reich Citizenship Act of 27 September 1938, he was banned from working as a lawyer. Deprived of his revenue, he rapidly used up his savings to cover his living expenses and organization of his flight. He was ultimately forced to sell ethnological objects from his collection to the Museum of Folk Life and Folk Art, two musical instruments to the Kunsthistorisches Museum, music manuscripts to the City Library, and fashion items to the Städtische Sammlungen Wien. He had already sold objects to the last-named before 1938 and knew what it was interested in. On 15 September 1939, Karl Wagner, director of the Städtische Sammlungen, applied to the Central Monument Protection Office to secure the Fuchs collection, referring to its threatened "disappearance" abroad. The Central Office rejected the application, as an offer from the Städtische Sammlungen to Fuchs already existed, but it also informed other institutions about the collection. Music manuscripts and printed scores were ultimately acquired by the Music Collection at the National Library, fashion items and Viennensia by the Städtische Sammlungen, militaria by the Museum of Military History, and designs for ground glass by the Arts and Crafts Museum. Although Fuchs had been issued export authorization on 14 June 1940 for the rest of his collection, he appears to have been unable to take anything with him when he fled in December 1940. He reached Shanghai via the USSR, where he died in 1946.
During the systematic provenance research by the city of Vienna, in 2002 the Vienna restitution commission recommended the return of objects owned by Siegfried Fuchs to his heirs. Similar decisions were passed by the federal Art Restitution Advisory Board in 2005 for objects in the Austrian National Library, in 2006 for objects in the MAK and in 2012 for those in the Kunsthistorisches Museum. Further restitution recommendations by the Art Restitution Advisory Board were made in 2015 and 2021 for objects from the Fuchs collection in the Museum of Military History.