Koji Toyoda began his violin studies with Shinichi Suzuki at the age of three and a half, and continued his studies at the Conservatoire National Superieur in Paris. He later improved himself with Georges Enescu and Arthur Grumiaux. He received the Bach medal of Harriet Cohen Music Awards in London and also awards at international competitions in Paris, Geneva and Brussels.

From 1962 to 1979, he was concertmaster of the Radio-Symphony-Orchestra in Berlin. From 1979 to 2000, he was a professor at the Hochschule der Kunste in Berlin. He was one of the founders and the first Artistic Director of the Kusatsu International Summer Music Academy and Festival, and the Director of the Gunma Symphony Orchestra.

He assumed the Presidency of the Talent Education Research Institute after Shinichi Suzuki passed away in 1998 and he is also President of the International Suzuki Association. Some of his compositions are published by the Zen-On Music Publishing Co.