First-Prize winner of the Japan National Music Competition in 1960, Ko Iwasaki studied cello with Hideo Saito. After graduating from the Toho Music School in Japan, he continued his studies at the Juilliard School under Leonard Rose. In 1965 he made his New York debut in the Young Concert Artists Series. Later, he studied with Harvey Shapiro and Pablo Casals in Puerto Rico. He has won top prizes in numerous international cello competitions such as the Vienna, Munich, Budapest, Cassado, and Tchaikovsky competitions. 

In 1971, he received the Arts Minister Award for Young Artists and the Arts Festival Record Prize for his performance of contemporary Japanese cello music. In 1972, he made his European debut with the London Symphony Orchestra with Andre Previn.

Since 1974, he has been based in the United States where he has performed both as a soloist and as a chamber music player, as well as in Europe, the former Soviet Union, and Japan. In addition, he has participated in numerous festivals, including Marlboro, Aspen, Santa Fe, Lockenhaus, and Kuhumo. He is also a founder of the Tokyo Chamber Soloists and was a director of the Okinawa Moon Beach Music Camp & Festival in Japan. Since 1995, he has performed the entire cycle of Beethoven String Quartets as a member of the Japan String Quartet.

He has taught at Illinois State University, University of Illinois and the Southern Methodist University. He also has been highly praised for his master classes conducted at the Cleveland Institute of Music, the World Cello Congress, universities and summer music festivals. Since 1990, he has been invited to serve as a jury at many international competitions including the Cassado Cello Competition, the Munich International Competition, and the Tchaikovsky Competition. Residing in Dallas, Mr. Iwasaki continues to pursue an active concert career, while teaching at the Toho Conservatory Graduate School in Japan.