Mary Yuriko "Yuri" Kochiyama, nee Nakahara was born on May 19, 1921, in San Pedro, CA, to Japanese immigrants Seiichi Nakahara, a fish merchant entrepreneur, and Tsuyako (Sawaguchi) Nakahara. She had a twin brother, Peter, and an older brother, Arthur. In her youth she attended a Presbyterian church, taught Sunday school, and attended San Pedro High School, where she served as the first female student body officer, wrote for the school newspaper, and played on the tennis team. She graduated in 1939. She attended Compton Junior College, Compton, CA, where she studied English, journalism, and art. Kochiyama graduated in 1941.

On December 7, 1941, her life was put in disarray, when the Empire of Japan bombed Pearl Harbor at Oahu, Hawaii. President Franklin D. Roosevelt issued Executive Order 9066, which forced out approximately 120,000 people of Japanese ancestry from the Pacific coast and interned them at various camps across the United States. Yuri, her mother, and her brother were transferred forcibly to a converted horse stable at the Santa Anita Assembly Center for several months and then moved again to the War Relocation Authority internment camp at Jerome, AK, where they lived for the next three years. While interned, she met her future husband, Bill Kochiyama, a Nisei or second generation Japanese.

In 1946, Yuri married Bill Kochiyama, a veteran of the 442nd Regiment. The couple moved to New York City where her political activism would flourish. In 1960 the family moved to a low-income housing project in Harlem. Yuri and her family invited many civil rights activists, such as the Freedom Riders, to their home gatherings. They also became members of the Harlem Parents Committee, a grassroots organization fighting for safer streets and integrated education.

In October 1963, at a protest against the arrest of about 600 minority construction workers in Brooklyn, Kochiyama met the African-American activist Malcolm X, the Black Muslim minister, prominent member of the Nation of Islam and for and for a time its spokesperson. Malcolm X helped radicalize her and Kochiyama joined his Pan-Africanist Organization of Afro-American Unity. She was present at his assassination on February 21, 1965, at the Audubon Ballroom in Washington Heights, New York City, and held him in her arms as he lay dying – a famous photo appeared in Life magazine capturing that moment.

In the Vietnam War period and after, Kochiyama became a mentor to the radical wing of the Asian American movement. As organizers of East Coast Japanese Americans for Redress and Reparations, for example Yuri and Bill Kochiyama advocated for reparations and a government apology for the incarceration of Japanese Americans during World War II, and spearheaded the campaign to bring the Commission on Wartime Relocation and Internment of Civilians to New York. Additionally, Kochiyama founded the Day of Remembrance Committee in New York City to commemorate the day President Franklin D. Roosevelt authorized Executive Order 9066, which caused the forced removal and incarceration of Japanese Americans during World War II. President Ronald Reagan signed the Civil Liberties Act in 1988 which awarded $20,000 to each Japanese American internment survivor. Kochiyama used this victory to advocate for reparations for African Americans. In later years, she and Bill were active in opposing profiling of and bigotry against Muslims, Middle Easterners, and South Asians in the United States, a phenomenon she viewed as similar to the experience of Japanese Americans during World War II. Their continued dedication to social causes would inspire younger generations of activists, especially within the Asian-American community. Bill Kochiyama died in 1993.

In addition, Yuri Kochiyama was also known for her support of and advocacy for the rights of political prisoners. Kochiyama defined a political prisoner as an individual, who has been a movement activist before being imprisoned; has had some association or affiliation with a recognized political group such as the Black Panthers, Young Lords, American Indian Movement, Red Guards, Republic of New Africa, the Student Nonviolent Coordinating Committee (SNCC),the Congress of Racial Equality (CORE) etc.; or has engaged in some action, including clandestine acts which were political. She also included in this definition many politicized prisoners, who went to prison on some social violation but became heroes to movement activists. In this regard, she advocated on behalf of such prisoners as the Black Liberation Army member Mtayari Shabaka Sundiata, former Black Panther adherent Mumia Abu Jamal, American Marxist revolutionary Marilyn Buck, Japanese Red Army member Yu Kikumura, Puerto Rican nationalist Lolita Lebron, Black Nationalist Assata Shakur and indigenous rights activist Leonard Peltier.

On the international level, Kochiyama backed the work of the Communist Party of Peru or the Shining Path and the Venceremos Brigade, which challenged U.S. policy towards Cuba. At home, she also taught English to immigrant students and volunteered at soup kitchens and homeless shelters in New York City. In 2005, Kochiyama was one of 1,000 women collectively nominated for the Nobel Peace Prize through the "1,000 Women for the Nobel Peace Prize 2005" project. In 2010, she received an honorary doctorate from California State University, East Bay. On June 1, 2014, Yuri Kochiyama passed away at the age of 93 in Oakland, CA.