[1] Warren taught home economics at Columbia until 1917, at which time she moved to Washington, D.C. to join the United States Department of Agriculture (USDA) as a senior scientist.

She was placed in charge of the home-making element of a network of boys' and girls' clubs,[1] organized under the Cooperative Extension Service.

[1] Warren expanded the scope of girls' activities under the program (promoting garment making, room decorating, and hot lunches), and wrote extensive training materials.

[1] To sum up her career, she was called "the mother of 4-H"[1][8] and "the guardian angel of 4-H."[6] Outside of government, Gertrude L. Warren was president of the Woman's National Farm & Garden Association from 1952 to 1954.

[10] At the National 4-H Conference Center in Chevy Chase, Maryland, the headquarters building was named Warren Hall in her honor.