Guilbeault first got noticed on the Montreal jazz scene in the groups of pianist Jean Beaudet and drummer Bernard Primeau in 1985. From the start, his ease of play, elegant improvising, and clean sound were appreciated. He soon recorded his first studio session: Primeau's Perspectives, released in 1987. Performances and recordings alongside Yannick Rieu, Nelson Symonds, and François Marcaurelle followed before the end of the decade. Meanwhile, the bassist formed his Norman Guilbeault Ensemble in 1988. First a quartet comprising trumpeter Ivanhoe Jolicoeur, clarinetist Mathieu Bélanger, and drummer Paul Léger, it expanded to a quintet with the arrival of trombonist Michel Ouellet in 1991. Guilbeault's intent was to have a bass-led group in the vein of Charles Mingus' and Oscar Pettiford's, with a repertoire of compositions by bassists. But with the years, the group developed its own repertoire, gradually moving out of jazz standards and into something more contemporary. A first album, Dualismus, came out on Red Toucan in 1994, the same year the Ensemble won the DuMaurier Jazz Award at the Montreal Jazz Festival. Two more CDs with Jean Derome as guest followed in 1995 and 1996 on Justin Time. The Jazz Report Magazine from Toronto declared the Ensemble Best Jazz Acoustic Group of 1997.
Derome opened a door to the avant-garde scene and the bassist's interests began to shift. His playing grew freest while retaining a strong jazz flavor. By the mid-'90s, Guilbeault had completely renewed his roster of collaborators and become a trusty sideman for most key Ambiances Magnétiques artists. He contributed to Derome's large-scale projects, Michel F. Côté's soundtracks and his group Bruire, Robert M. Lepage's free jazz trio, and René Lussier's ensemble. Supported by the label, he created his +Riel at the Festival International de Musique Actuelle de Victoriaville in 1998 and toured it in Canada for a couple of years. A recording came out in 1999. In 2000, Guilbeault joined forces with Marcaurelle, Jean Vanasse, and Pierre St-Jak to organize the first OFF Montreal Jazz Festival. Born out of a profound dissatisfaction with the official event's focus on big international stars, the OFF programmed local jazz musicians, premiered encounters, and presented left-field music the real festival disregarded. The OFF was back the next year with support from the alternative press. ~ François Couture, Rovi