The main reason for this decision was the fact that Stan Kenton was looking for a featured trombonist. Kai got both the job and the task "to take care of the trombone section".Until that time, the trombone section didn't have an identifiable sound. Kai gave it the unique sound that remained with the orchestra. That section had, besides Kai, players like Harry Forbes, Skip Layton, Milt Bernhart and Bart Varsalone in it.

As Kai recalled: "The arrangements were tricky and required more than only band rehearsals, so I used to get the trombone section together and we would decide how certain things should be phrased. Instead of a slide vibrato I would rather use a lip vibrato. Being lead trombonist the other trombonists would match this".

There were a lot of solos in the repertoire which were played by Kai. Very Well known are Machito, Concerto to end all concertos and Collaboration, a tune specially written for him by Pete Rugolo.

Besides the intensive recording sessions with Stan there were also recordings with Vido Musso and Allen Eager.

But also the Stan Kenton Orchestra didn't give sufficient stretch-out room for a jazz-orientated player like Kai, so after a year and a half, when Kenton broke up, he left him for Charlie Ventura's jazz combo, an epitome of freedom. That combo included at that time (Fall 1947) Shelly Manne, Lou Stein, Buddy Stewart and Bob Carter.

Again after 18 months it was time for a change. He left Charlie Ventura and went with Woody Herman for a short period.

Soon after, Kai was to be found in the 52nd Street area. He fronted his own combos which included Brew Moore and George Wallington, but also also played as sideman with Brew Moore and Gerry Mulligan. It was about this time that he had his first sessions with J.J. Johnson in a studio big band led by Chubby Jackson and in the 1949 Metronome All Stars.

During this period, he played a lot with Tadd Dameron, Charlie Parker, Miles Davis and Allen Eager in Birdland and Bop City. He recalled this period as being very special.

After this excitement there came the bread and sweat of studio work. By this time, he and his wife had two sons.

He stayed in town and could be seen playing in the Robert Lewis CBS show with Ray Bloch's Sextet and in the Patti Page Show. Besides that, he did a lot of commercials, and, whenever it fit in his schedule, played as many sessions around town as possible.There were a lot of recordings with all kinds of orchestras and combos. One week he could be found playing in Woody Herman's Big Band, the other week in the small group of Eddie Shu to mention some. This lasted until August 1954. It was Ozzie Cadena, the Savoy producer, who got the idea of recording a group with a front line of two trombones. He asked J.J. Johnson to do the recording together with Benny Green. As the latter was not able to do the recording due to contracts with his own group, another trombonist as asked: Kai Winding. Kai and J.J. already had played together on several occasions, so they knew and admired each other's style of playing. That first recording was done in one day and not on two dates as is often mentioned. This recording was also the birth of probably of of the most famous jazz groups: Jay and Kai, or K and JJ.

In order to get their names rhyming, Kai's name had to be pronounced wrongly as Kay. His name had been pronounced incorrectly since the time he was with Charlie Ventura's combo, and one day someone announced: "with Jackie Caine on trombone and the lovely Mrs. Kay Winding on vocals."

During the time Kai played with J.J. his style changed. Before that, he played in a bold, emphasis manner which could not be mistaken with any other player. It is a very well known fact that they, on some of the latter of the Kai & JJ recordings, are very difficult to distinguish. His playing had become smoother and warmer, but his musical ideas had remained the same. In the quintet, he and J.J. also started to play the trombonium. Kai has used this instrument, which sounds like a valve trombone but looks like a bended euphonium, also on later occasions.

The quintet enjoyed very good rhythm sections with men like Charlie Mingus, Milt Hinton, Dick Katz and Osie Johnson.

In February 1955, Kai's wife Marie died, and left him with three children (she already had a daughter when they married).

Kai remarried with Jeanne Tart shortly after, in July 1955.

At the Newport Jazz Festival in July 1956, each of the trombonists went his own way. Although they would make records even into the sixties, the Kai and J.J. Quintet didn't exist anymore. J.J. started his own quintet, and Kai started the septet featuring four trombones.

Right from the start, the Kai Winding Trombones, or the Kai Winding Septet as it was sometimes called was very successful. Their first recording was in August 1956 with men like Carl Fontana, Wayne Andre and Dick Lieb in the front line.

In January 1957 his daughter Michelle was born.

The Kai Winding trombones did a lot of traveling and endless jobs at college campuses and in jazz clubs.

Many young talented players like Tony Studd, Bill Watrous and Ross Tompkins were part of the group. The traveling and performing slowed down when Kai accepted a job as musical director in the Playboy Clubs at the end of 1962. His job was to set up the music policy for the Playboy clubs. He cut down his own orchestra to a quartet and played quite a lot himself in Playboy Clubs, too.

The music more and more left the jazz field. In 1963 he made a beautiful recording with his quartet (Solo), but the recordings he made after this one were more in a popular idiom.

He acclaimed national reputation with the recording of the song "More".

Also, the recordings with his septet turned out to be less jazz than usual.

At the end of the 60s Kai played a short time in The Worlds Greatest Jazz band, where he replaced Carl Fontana.

In 1969 he went back into the studios again. He also joined the band of the Merv Griffin Show. New records were made with J.J. for the A&M Record Company.

One year later he was faced with a major decision when the Merv Griffin Show moved to Los Angeles. This was not the only show which moved west, so also a lot of writers, arrangers and musicians went there.

Kai followed and immediately found himself busy in the Hollywood studios. He rejoined Merv Griffin but started also a major tour with the Giants of Jazz, the group which included Dizzy Gillespie, Sonny Stitt, Kai Winding, Thelonious Monk, Al McKibbon and Art Blakey. This tour was in 1971 and 1972.

There were also in increasing lot of campus concerts and clinics for the outfit he was associated with since 1941, King Musical Instruments. With that company, he developed his own type of trombone which is based on their 2B trombone model.

He got involved again in the jazz music. After the Giants of Jazz tour he was still working with the Merv Griffin and Sammy Davis Jr. shows but he also started performing and recording with his own quartet for the Glendale label.

Kai and his wife Jeanne were divorced in 1975.

After his marriage with Eleanor Hamilton on September 13, 1977, they moved to Spain. The main reason for this decision were the facts that he and his wife wanted to simplify their lives, and that Kai had decided to stop studio music. From that time he only played his own music. Considering these facts it is not a coincidence that most of Kai's compositions were made between 1975 and 1982. Between his performances all over the world he devoted a lot of his time to composing and arranging.

In this period, he also organized the orchestra for the "Children of Sanchez" and other records of his long time friend Chuck Mangione. They had met in 1956 when on one occasion Kai let the young Chuck sit in with his band.

Together with Curtis Fuller he formed another two-trombone group in 1979. The Giant Bones, as they called themselves, played at many places. They made two recordings, one for the Sonet label and one for Ahead.

He also performed and recorded with the New Mel Lewis Quintet, and with a group of four trombones for PAUSA. The other trombonists were Albert Mangelsdorff, Jiggs Whigham and Bill Watrous.

The Giant Bones could be heard at major festivals in Nice (France), The Hague (Holland), and in a lot of jazz clubs all over the world.

Once more, for the final time as it turned out to be, Kai and J.J. were reunited. They played at the 1982 Aurex Jazz Festival in Japan as members of the Aurex Jazz Festival All Stars.

His final performance was in London in December 1982. After coming home from London, he and his wife went on for what was to be a short holiday in Portugal. The main reason was that Kai felt himself tired. On the second day of their holiday, Kai suffered severe headaches. After a diagnosis in Spain, Eleanor had to rush Kai into a New York Hospital where a brain tumor was diagnosed.

He got a first operation shortly before Christmas, from which he recovered quite soon. After a short stay in the Bahamas, he had to be taken into the hospital for a second time. A second operation took place at the end of April 1983. Kai died on May 6, 1983 due to complications from the second operation.