Lassy is a Helsinki native. He began playing the tenor sax as a pre-teen and, showing an aptitude for technique and composition, was educated at the Finland's famous Sibelius Academy. He was a part of the Nu Spirit Helsinki movement early on and played with a wide swath of pop, R&B, electronic, and jazz musicians including Ultra Bra, Tino Singh, and Tommi Läntinen before joining U-Street All Stars for the Helsinki Sessions in 2002; the band also included bassist Timo Tuppurainen. That same year, Lassy joined the Five Corners Quintet. Originally created as a studio project, the group's energy was too intense to be contained in an enclosed atmosphere. They established their considerable reputation on stages across Europe, Asia, and the U.S. While they cut Chasin' the Jazz Gone By with American singer and songwriter Mark Murphy in 2005, they cut a follow-up with him entitled Hot Corner in 2008. A year later the saxophonist recorded his debut solo outing, The Soul Jazz of Timo Lassy for Ricky-Tic Records, followed in 2009 by Round Two, a collaboration with American singer Jose James; he founded the Timo Lassy Band the same year, whose membership included double bassist Antti Lötjönen, drummer Teppo Teddy Rok Mäkynen, and percussionist Abdissa Mamba Assefa. 2010 saw the release of the Five Corners Quintet's live The Helsinki Sessions and a world tour.
In 2012, Lassy re-entered the studio for Italy's Schema label and emerged with the critically acclaimed In with Lassy. Touring with his own group resulted in Live with Lassy -- another Schema offering -- in 2014 before heading directly back into the studio with his own band and fellow Five Corners' alumnus trumpeter Jukka Eskola. The resulting album, Love Bullet, on Germany's Membran-associated Must Have Jazz imprint, garnered more positive reviews and also sold better than his all previous dates combined. Lassy collaborated with Brazilian songwriter and multi-instrumentalist Ed Motta for the 2017 EP When the Devil's Paid. It was playlisted on the U.K.'s Jazz FM and remained near the top of the jazz charts for five consecutive weeks. Though Lassy's band continued to tour, they dashed into a studio to emerge with Moves (also on Must Have Jazz) the following year; it placed on virtually every Western European jazz streaming chart. It encompassed the various elements that had informed his sound from the beginning: '60s soul, Latin jazz, soulful vocal jazz, electronic sounds, and even hip-hop. In 2019, Lassy and Mäkynen collaborated on a self-titled duo date for the Helsinki-based We Jazz label (a companion label to the internationally renowned festival). It marked a return to adventurous hard- and post-bop. Prefaced by the 7" single "Zomp" b/w "Dark Magenta" in February, the full-length was released in the spring to great anticipation. ~ Thom Jurek, Rovi