1969, Kazuhiro Koizumi entered Tokyo University of the Arts, where he studied
conducting with Kazuo Yamada. After being awarded first prize in the second
Min-On Concert Association of Japan Conducting Competition in 1970, he went on
to become Assistant Conductor at the former Japan Philharmonic Orchestra, and
was one of the conductors of the New Japan Philharmonic upon its founding in
July 1972. Later in October of the same year, he began studying opera
conducting at the Berlin Hochschule with professor Hans Martin Rabenstein.
He continued his studies in the summer of 1973 with his participation in the Tanglewood Music Festival .
In November 1973, he was awarded First Prize at the 3rd Herbert von Karajan International Conducting Competition, and then debuted in Berlin as a conductor with the Berlin Philharmonic.
He served as Music Director of the New Japan Philharmonic from 1975 to 1979. After a highly successful appearance with the Berlin Philharmonic at its subscription concerts in March 1975, he continued conducting around Europe to great acclaim in places like Vienna, Paris, Italy and the former West Germany.
In January 1976, he appeared with Orchestre Philharmonique de Radio France, performing with the legendary Anton Rubinstein and Mstislav Rostropovich, and he conducted the Vienna Philharmonic at the Salzburg Festival later the same year. His vast conducting credits throughout Europe include the Munchner Philharmoniker, the Symphonieorchester des Bayerischen Rundfunks, and the Philharmonia Hungarica. In the US, his triumphant performance with Chicago Symphony Orchestra at the Ravinia Festival in 1978 led him to an engagement leading the group in an acclaimed subscription concert in March 1980, two years later. He has guest conducted numerous orchestras including the Boston Symphony Orchestra, Detroit Symphony Orchestra, Cincinnati Symphony Orchestra, Toronto Symphony Orchestra, Montreal Symphony Orchestra.
He was Music Director of Canada's Winnipeg Symphony Orchestra from the 1983/84 through 1988/89 seasons, and he conducted the Tokyo Metropolitan Orchestra from 1986 to 1989. Since 1988, he has been invited to conduct regularly by London's Royal Philharmonic Orchestra, and they have also completed recording Tchaikovsky's Symphonies No. 4, 5, and 6 together.
Koizumi has served as the Principal Conductor of the Kyushu Symphony Orchestra from April 1989 to March 1996, the Guest Principal Conductor of the Century Orchestra Osaka from April 1992 to March 1995, the Principal Conductor of the Tokyo Metropolitan Symphony Orchestra from April 1995 to March 1998 and the Principal Conductor of the Century Orchestra Osaka from April 2003 to March 2008. Since April 2006 he has been Principal Guest Conductor of the Sendai Philharmonic Orchestra, and since April 2008 both the Music Director of the Century Orchestra Osaka (current Japan Century Symphony Orchestra), and a Resident Conductor of the Tokyo Metropolitan Symphony Orchestra.