Guillaume Bellom has one of the most atypical careers of his generation, studying violin, alongside the piano, from the Besançon Conservatory to the CNSM in Paris. It is through the contact with outstanding musical personalities, such as Nicholas Angelich and Hortense Cartier-Bresson, that he fully develops his activity as a pianist.

Finalist and "Modern Times" prize for the best interpretation of the contemporary piece in the Clara Haskil competition in 2015, he is revealed at this event dedicated to the Romanian pianist, herself a violinist at her time. The same year, he won first prize in the international Epinal competition and became a laureate of the L'Or du Rhin foundation, before winning the Thierry Scherz prize at the Gstaad Musical Summits the following year. The general public discovered him during the Victoires de la Musique 2017, where he was nominated in the category "revelation soloist instrumental". He is also an artist in residence at the Singer-Polignac Foundation since 2012.

 He has performed as a soloist with the Lausanne Chamber Orchestra, the Camerata du Léman, the Orchestre National de Lorraine, under the direction of Jacques Mercier and Christian Zacharias. He regularly performs at numerous festivals with artists such as Renaud Capuçon, Amaury Coeytaux, Nicolas Dautricourt, Philippe Cassard, Paul Meyer, Yan Levionnois, Victor Julien-Laferrière and Antoine Tamestit.   His discography includes two albums dedicated to works for four hands by Schubert (awarded by a "ffff" Télérama) and Mozart, recorded with Ismaël Margain for the label Aparté, a sonata disc with cellist Yan Levionnois, released in 2017 for Fondamenta (awarded by a "ffff" Télérama), and a solo disc released by Claves the same year, dedicated to Schubert, Haydn and Debussy.