As a teenager Werner took lessons in harmony and learned the tenor saxophone in his hometown of Stockholm. His early influences included such jazz musicians as Charlie Parker, Lennie Tristano, and Tadd Dameron, as well as European classical masters like Anton Webern and Arnold Schoenberg. In the early ‘50s he dropped the tenor in favor of piano. By 1956 he was touring Europe with his own quintet. That year he played with Lester Young in a West German nightclub; the performance was broadcast and the music later released on an album entitled Pres in Europe. The meeting with Young had a profound effect on Werner's decision to pursue a career in jazz. In the late ‘50s Werner recorded with the tenor saxophonist Bernt Rosengren. A relationship with bassist Kurt Lindgren took root and flourished in the ‘60s. The pair was part of a group of musicians who performed at the Golden Circle club in Stockholm, and they also worked together in a staging of Jack Gelber's jazz-oriented play, "The Connection." Werner and Lindgren formed a band that included the saxophonist Christer Boustedt. Inspired by experimental classical composer John Cage and '60s-era performance art, the group incorporated absurdist theatrical elements into their performances. In the late ‘60s Werner split with Lindberg and formed Lasse Werner and His Friends; during the ‘70s he would perform with the group in various permutations which often included Boustedt. After falling into a diabetes-induced coma in 1978, Werner was forced to withdraw from music. He never recovered fully, although he did make something of a comeback in the years just prior to his death in 1992. In addition to his work as a player, Werner was also a respected writer on jazz.