Following two successful concerts in Belgium, T21 signed to Brussels-based industrial/goth label Play It Again Sam, greatly increasing their visibility. The 1985 EP Wait & Dance was issued by PIAS' short-lived Scarface imprint, followed by the 1986 full-length Chapter IV: Le Je-Ne-Sais-Quoi et le Presque Rien, which contained the group's biggest hit, "The Last Song." A re-recorded, remixed version of the album appeared in 1987, as did the full-length Million Lights, which appeared on PIAS proper following the Scarface sublabel's closure. The album was created solely by the Lomprez brothers, without a bass player, and was significantly more electronic than their past material. Arriving in 1988, Works marked the debut of guitarist Bruno Objoie, who also contributed to the more atmospheric Plays the Pictures (1989) and live album Raw Material (1990).

The 1992 full-length Distant Voices, which featured Tuxedomoon violinist Blaine Reininger and backing vocalist Lena Kane, found the group experimenting with jazz, pop, and cinematic textures, resulting in some of their strangest yet most accessible work. However, disputes with their label would delay their next album by several years. Following the release of three compilation CDs, 1987's ambient-influenced Gohohako would be T21's final album for PIAS.

The group went on hiatus for a while, but returned in 2003, when they were asked to remix the song "Le Grand Secret" by French pop/rock band Indochine. The comeback album Happy Mystery Child was released by Le Maquis in 2004, followed by a series of remix albums featuring producers from throughout the techno, electro, and EBM scenes. In 2007, the Belgian label Alfa Matrix released T21's live album Rendez-Vous en France, some copies of which included a CD of early rarities and demos. The group's final release on Le Maquis, 2009's Black Label, was one of their heavier, more driving releases.

The group embarked on what they assumed would be their final tour, playing one last gig in Brussels. However, the Lomprez brothers secretly returned to the studio in 2017, with early member Tison contributing to some of the sessions. The full-length Elegance Never Dies was released by the group's own Chromo Music Production by the end of the year, and the group toured throughout Europe in support of the album. Additionally, the American label Dark Entries released Chapter I-IV, a vinyl box set containing expanded editions of T21's first four records, which were also reissued individually. The group also released a three-CD box set of early material titled Originally in 2018. ~ Paul Simpson, Rovi