Guillaume Couloumy started trumpet with Bruno Gorce at Limoges Music conservatory where he got a first prize and a gold medal. He moved then to Germany and integrated the trumpet class of Professor Max Sommerhalder at the college of music Detmold. During this period he also worked with many important musicians and teachers like Reinhold Friedrich, Bo Nilson, Franck Pulcini, Hannes Läubin, Gabor Tarkövi. After his graduation in Detmold in 2002 he immediately won the audition for the academy of the BR Sinfonie Orchestra of Bavarian radio, Munich. In 2003 he won 3rd prize and the public award at the international competition of Munich ARD.

As soloist he had the opportunity to perform with Berlin Konzerthausorchester, Berlin Chamber Orchestra, Berlin Sinfonietta, Munich Radio Orchestra, Munich Chamber Orchestra, NDR Elbphilharmonic Orchestra Hamburg. Furthermore he gives regular recitals with piano or organ, and many chamber music concerts with brass quintets and the NDR Brass ensemble.

Guillaume Couloumy substituted in many orchestras as principal trumpet like in Mahler Chamber, orchestre national de Radio France, opéra national de Paris, accademia di Santa Cecilia Roma, Gewandhaus Leipzig, BR Munich, HR Frankfurt, SWR Freiburg, RSB and DSO Berlin, Berlin Deutsche Oper and Staatskapelle, and Berlin Philharmonic under conductors Claudio Abbado, Riccardo Muti, Zubin Meta, Pierre Boulez, Maris Jansons, Simon Rattle, Kirill Petrenko. After 3 years as principal trumpet of Konzerthausorchester Berlin, he is since 2007 principal trumpet in the NDR Elbphilharmonie orchestra Hamburg. Furthermore he his also teaching at the college of music in Lübeck.