Johnnie Phelps was born Nell Louise Phelps in North Carolina on April 4, 1922 and was raised with an adoptive family. Her adoptive parents were abusive, and Phelps spent many of her teen years in and out of jail.

By the 1940s, Phelps married a Navy man, but they constantly fought, and she sought to escape by joining the military in 1943. She served as part of the Women's Army Corps (WAC) and was honorably discharged in 1945. She re-enlisted in 1946 and was honorably discharged a second time. Phelps left the army to establish her own printing business, which she ran for years. Living in Southern California, Phelps became politically active in the 1970s. It was around this time that she met her partner, Grace Bukowski.

Phelps joined the National Organization for Women and founded the San Gabriel Valley - Whittier chapter in 1979. She chaired the California Lesbian Task Force (a branch of NOW), and spearheaded protests on behalf of the Norton Sound Eight--eight female crew members aboard the USS Norton Sound who were charged with "homosexual misconduct." In addition, she joined the Southern California Women for Understanding organization and served on the Los Angeles County Veterans' Advisory Commission. A recovering alcoholic, she also served as president of the Alcoholism Center for Women.

Phelps died on December 30, 1997 at the Veterans Home in Barstow, California at the age of 75. She is buried in Veteran's Cemetery in Westwood, California.