Foster never knew who her father was and she moved to Janesville, Wisconsin after her mother was hospitalized for a mental illness.

[5] Foster became one of the few African Americans at the Goodman School of Drama at the Art Institute of Chicago (now at DePaul University).

During her studying at the Goodman School she also, "learned professional acting skills in the Court Theater at the University of Chicago".

[4] Foster was known for her work with Joe Papp, and appeared in his productions of Long Day's Journey into Night, Chekhov's Cherry Orchard, Brecht's Mother Courage (adapted by Ntozake Shange), and Shakespeare's Coriolanus.

Nothing But a Man (1964) – Gloria Foster plays a woman named Lee, who lives with the main character's (Duff Anderson) father.

Her character in both Law and Order episodes, named Satima Tate, was based on the widow of Malcolm X, Betty Shabazz.

The second episode, titled Entrapment (1997), focused on her character's children's acts of revenge against the people they believed were really responsible.

While Foster did not have many close relatives, she stayed in contact with her Delta Sigma Theta sorority sister, Cicely Tyson.

At the end of the scene each night, there were tears streaming down her face, her body was trembling, but her dignity was intact ... Foster had to be covered with blankets in order to calm her shaking".