In 1960, Kochiyama and her spouse moved to Harlem in New York City and joined the Harlem Parents Committee. She became acquainted with Malcolm X and was a member of his Organization of Afro-American Unity. She was also present at Malcolm X’s assassination on February 21, 1965, at the Audubon Ballroom in Harlem, and held him in her arms as he lay dying.
In 1977, Kochiyama joined the group of Puerto Ricans that took over the Statue of Liberty to draw attention to the struggle for Puerto Rican independence.
Over the years, Kochiyama has dedicated herself to various causes, such as the rights of political prisoners, freeing Mumia Abu-Jamal, nuclear disarmament, and reparations to Japanese Americans who were interned during the war.
In 2005, Kochiyama was nominated for the Nobel Peace Prize through the “1,000 Women for the Nobel Peace Prize 2005” project.