Ricardo Muñoz was born on December 22, 1942, in Bisbee, Arizona. While his father, Rosalío, served in the U.S. Navy, Muñoz and his mother lived with his grandmother in Tucson, Arizona. Upon his father's return at the end of World War II, the family moved to Flagstaff, Arizona, where his father gained employment as a social worker. In 1947 the family moved to Los Angeles, where Rosalío enrolled in the USC School of Social Work; here he earned a master's degrees in social work and education. He went on to earn a doctorate in educational psychology, reinforcing for his children the importance of education.

The family moved frequently, living in Boyle Heights and then in the Maravilla Housing Project in East Los Angeles. In 1950 the family moved to the nearby neighborhood of Lincoln Heights, where Muñoz attended Avenue 21 Elementary School. In 1956 the family moved to nearby Highland Park, where Muñoz attended Nightingale Junior High School. He graduated from Benjamin Franklin High School in 1960.

After traveling in Mexico after his second year in college, Muñoz returned to Los Angeles in 1963 to continue his education. Upon his return, he attended school at UCLA, earning a bachelor's degree in finance in 1966. Following his undergraduate studies, Muñoz became a probation counselor with the Los Angeles County Probation Department and then a senior research assistant for the USC Public Systems Research Institute.

In 1968 he entered the UCLA School of Law, and in 1971 he received his juris doctorate. Since being admitted to the California bar in 1972, he has served the public, particularly the Latino community in Southern California, as an attorney at the Lincoln Heights branch of the Legal Aid Foundation and the Los Angeles Center for Law and Justice. In 1979 he became an administrative law judge with the California Unemployment Insurance Appeals Board; he was promoted to presiding administrative law judge in 1992. He retired in 2004.