Kochiyama's family said she died in her sleep Sunday.
Among her many accomplishments during 50 years of work, Kochiyama's activism led directly to the U.S. Senate's agreement to pay reparations and apologize to Japanese-Americans and others who were interred during the World War II.
Kochiyama was living in New York when she forged an unlikely bond with Malcolm X, and she witnessed his 1965 assassination in New York.
Kochiyama was born in San Pedro, California, to a middle-class family. She and her family were interred for two years in Arkansas during World War II. After the war, she moved to New York and married her husband, Bill, who died in 1993.
After her release at the war's conclusion, Kochiyama dedicated her life to social activism that spanned races, nationalities and causes, including vocal opposition of the Vietnam War and anti-apartheid policies in South Africa while supporting independence for Puerto Rico.
"Her tireless dedication to civil rights helped inspire generations of activists, including within the American Muslim community," the California chapter of the Council on American-Islamic Relations said in a statement. "She will be fondly remembered by all those of us who continue to defend civil liberties and promote justice."
The mother of six was living in New York's Harlem neighbourhood when she forged an unlikely bond with Malcolm X in the 1960s. She was sitting in the front row of the Audubon Ballroom Auditorium in New York when assassins burst in and gunned him down.
The California Assembly adjourned in Kochiyama's memory on Thursday.
Kochiyama is the author of a memoir, "Passing It On," and is survived by four of her children and several grandchildren.