[1] She attended the Punahou School with future U.S. President Barack Obama.

in Civil Engineering from Stanford University in 1983 and an M.B.A. from the UCLA Anderson School of Management in 1990.

Hamamoto began her career as a civil engineer for Pacific Gas and Electric Company, developing computer models to optimize hydroelectric energy generation in California.

During the 1990s, Hamamoto was as an investment banker with Goldman, Sachs & Co. and then at Merrill Lynch & Co, where she was a vice president in Corporate Finance.

The U.S. Mission to the United Nations in Geneva has, with her leadership, initiated a program, "The Future She Deserves", to address gender-based violence, adolescent girls' health, economic empowerment and leadership opportunities.