She attended night classes at John H. Francis Polytechnic High School in Los Angeles where she studied art.

After Garner had been working about six months, she auditioned for the voice of Minnie Mouse at the studio's sound stage, then located on Melrose Avenue.

Because Minnie was to play a Mexican in the upcoming film The Cactus Kid, Burt Gillett had asked the Ink and Paint department, which was entirely women, if anyone could speak Spanish.

Occasionally, Garner also provided additional voices, such as cat meows (Three Orphan Kittens, Lend a Paw), dog barking, and crowd noises.

During the Disney animators' strike of 1941, Garner shot home movies of the picket lines in color.

Her final role as Minnie would be in the 1942 war effort short "Out of the Frying Pan into the Firing Line".