After the war, Winding joined Benny Goodman's band, and later moved on to Stan Kenton's orchestra. Winding participated in the first of the Birth of the Cool sessions in 1949, appearing on 4 of the 12 tracks (while Johnson appears on the other eight, having participated on the other two sessions). In 1954, at the urging of producer Ozzie Cadena, he joined forces with Johnson to produce a highly successful series of trombone duet recordings, which were initially on Savoy Records and then on the Columbia Records label. While at Columbia, Kai experimented with different instrumentation in brass ensembles and also used a trombonium on at least one album that featured a trombone octet. Winding also arranged and/or composed many of the tracks he and Johnson recorded.
During the 1960s, Kai had a long stint at Verve Records and under producer Creed Taylor made some of his most memorable jazz-pop albums. His best known recording from this period is "More", the theme from the movie "Mondo Cane". This hit was arranged and conducted by Claus Ogerman. While at Verve, Kai further experimented with various ensembles, made solo albums, and even an album of country music with the Anita Kerr Singers. In the late 1960s, Kai followed Creed Taylor to his new recording label at A&M/CTi and made at least two more albums with Johnson.
In the 1970s and early 1980s, Kai recorded for a number of independent record labels. During this time, he continued to give clinics, play jazz concerts and even reunited with Johnson for a live concert in Japan. He also wrote instructional jazz trombone books that included transcribed solos.
Winding died of a brain tumor in New York City in 1983.