Koki Fujimoto was born in Tokyo. At the age of three he started to learn guitar. He has been taught by Noboru Muraji, Tomonori Arai, Kiyoshi Shomura and Tsuneo Ema. In 2016, his CD titled Guitar works by Toru Takemitsu was dedicated to the memory of Toru Takemitsu.
As a composer he has participated in the lessons of Miyuki Shiozaki, Sho Ueda, and Sunao Isaji.