Ikuko Mizuno began her violin training at age five, entering the Toho‑Gakuen School of Music in her native Tokyo and went on to win first prize in a national violin competition for high school students. She was a prizewinner in Japan's prestigious NHK Mainichi Shimbun Competition. Mizuno came to the United States as a winner of the Spaulding Award, enabling her to study with Roman Totenberg at Boston University, where she received her master's degree and was named a member of the honorary society Phi Kappa Lambda. In 2002 the Boston University College of Fine Arts awarded her the distinguished alumni award. In addition, she was a fellowship student at the Tanglewood Music Center. In Japan, Mizuno's teachers included Jeanne Isnard, Toshiya Etoh, and Saburo Sumi in Tokyo; she also studied chamber music with Hideo Saito. Mizuno also holds diplomas from the Accademia Musicale Chigiana in Siena, Italy, where she studied with Franco Gulli, and the Geneva Conservatory where she studied with Henryk Szeryng. While in Italy and Switzerland, she performed on radio and television.
In 1969, Mizuno became the first woman and the first Asian to be appointed to the Boston Symphony Orchestra violin section. Also that year, she and three of her BSO colleagues formed the Festival Quartet, which gave acclaimed performances throughout Massachusetts, including appearances at the Longy School of Music and at New England Conservatory's Jordan Hall. Mizuno made her New York recital debut at Carnegie Recital Hall in 1972. In the Boston area, she has appeared frequently at the Harvard Musical Association and at the Isabella Stewart Gardner Museum, and she has taught at the Massachusetts Institute of Technology, Boston University, Boston University Tanglewood Institute, Tanglewood Music Center, and as a guest professor at the Toho-Gakuen School in Tokyo. Mizuno has been soloist with the Boston Pops Orchestra and numerous other New England orchestras. As a chamber musician, she performs regularly on violin and viola with members of the BSO and other colleagues, including Yo-Yo Ma, harpist Nicolas Tulliez, and flutist Thomas Prévost. She has performed regularly in the Chicago area with Music of the Baroque, Mostly Music with Ko Iwasaki, and other groups.
Mizuno has returned frequently to Japan for recitals and performances with orchestra; in 1984 she was invited to be concertmaster for the inaugural concert of the Women's Orchestra of Japan. She performed in recital with composer and pianist Yehudi Wyner in Oji Hall in Tokyo at the invitation of The Mainichi newspaper. She was a member of the Saito Kinen Orchestra from its inaugural concert in September 1985, participating in European tours as well as in the Saito Kinen Festival at Matsumoto, Japan. In May 1990 Mizuno performed Tchaikovsky's Violin Concerto with the Leningrad Philharmonic under Fuat Mansurov, and with the Novosibirsk Symphony under Arnold Katz on concerts celebrating the 150th anniversary of the composer's birth; while in Leningrad, she also performed Vivaldi's Four Seasons under the direction of Alexander Poljanitchko.