Naoko Shimizu studied the violin under Etsuko Hirose and Toshiya Eto at the Toho Gakuen College of Music, where she also studied the viola under Nobuo Okada.

In 1993, she shifted her specialization to the viola and completed her graduate course of study.

From 1994, she studied under Nobuko Imai at Detmold University of Music. She won in the Markneukirchen International Instrumental Competition in 1995.

Shimizu has won prizes in numerous other competitions, including the highest prize of the 1996 Geneva International Music Competition (second prize, as there was no first that year) and first prize in the 1997 ARD International Music Competition in Munich, and she has also participated in the Tanglewood Music Festival and the Marlboro Music Festival.

Since February 2001, she has been active as the principal viola of the Berlin Philharmonic, as well as performing in chamber music and as a soloist with orchestras in Japan and overseas.