Guillaume Bouillon started playing the cello at the age of 9 at the Cambrai Conservatory in Emmanuel Puigdemont's class. He studied in parallel for two years with Odile Bourin at the Conservatory of the 10th arrondissement in Paris. He later studied with Hélène Dautry – whom he met during internships – at the Lille Conservatory. He graduated from music studies in 2009. In search of new horizons, Guillaume was admitted that same year to the Lausanne High School of Music and entered Patrick Demenga's class. He obtained his Bachelor's degree in 2012 and his Master of Performance Concert in 2014 with the same teacher. Guillaume continues to diversify his knowledge with the obtaining of a second Master of Education, obtained in 2016, with Marc Jaermann.

As a cellist, he is active in several orchestral formations. Replacement at the Lausanne Chamber Orchestra, the Geneva Chamber Orchestra, intern and then replacement at the Sinfonietta in Lausanne. In Chamber Music, he is the founder of the Eras Duo with guitarist Bruno Dias with whom he plays regularly. From 2014 to 2019, he took his place in the Ensemble Contemporain Sargo with which he worked in the form of workshops with D. Ammann's composition class at the Hochschule in Lucerne. Since 2015, Guillaume has been a member of the Diachronie Ensemble in Freiburg. In 2012 he performed as a soloist in the Concerto de Saint-Saens with the Allegro Passionnata Orchestra. In 2016 Guillaume performed Haydn's Concerto with the OJSR as a soloist. He performs solo and chamber music at various festivals: Bach Festival in Lausanne, solo. Festival of Music Gardens, with the Sine Nomine Quartet, and Montreux Jazz Festival as a quartet. It is also regularly found in original projects with other artists such as with the Cantamisù Theatre Company or various projects with dancers. A grant from the Irène Dénéréaz Foundation is awarded to him in 2018.

Guillaume is passionate about pedagogy and teaching. He has been a professor since 2016 at the School of Music of Épalinges, and since the beginning of 2017 at the Conservatory of Music of the North Vaudois in Yverdon-les-Bains. He regularly attends Mediation Concerts where he creates interactions for adults, the elderly and children. In 2016, he was awarded the Paleo Scholarship for his mediation work. Guillaume continues to improve his skills through Masterclasses and internships with great performers such as Jérôme Pernoo, Anthony Leroy, Franz Helmerson, Gary Hoffman, Orfeo Mandozzi and the Debussy Quartet. In 2019 Guillaume performs in chamber music with various bands and artists; on ice with Stephane Walker, Swiss figure skating champion; trio and also in the duo "Vibrations of Wood and Metal" with the flutist Yu-Hsuan Kuo in Switzerland and France. Both are part of the Association "The Concerts of the Heart" which engages through concerts and workshops with the elderly, hospitalized and orphans.