Ella Graham Agnew, daughter of Dr. James A. and Martha Chaffin Scott Agnew, was born in Prince Edward County, Virginia on March 18, 1871; soon afterward, the family's home was destroyed by fire, and the Agnews moved to Nottoway County, Virginia. After studying stenography at Smithdeal Business College (Richmond, Virginia), Agnew was hired as a secretary at Stonewall Jackson Institute, a women's college in Abingdon, Virginia. Around 1894, she moved to Long Island, New York, where she briefly worked as a secretary for a publisher before moving to South Africa to teach secretarial courses at Huguenot Academy in Paarl. She then served as principal of Amajuba Seminary (Wakkerstrom).

Returning to the United States ca. 1900, Agnew held several positions before becoming involved in the education of rural girls in Virginia. In 1910, she created a vocational education system through tomato and canning clubs in Nansemond and Halifax counties, becoming the nation's first woman home demonstration agent. When administration of the state's home demonstration was transferred from the U. S. Department of Agriculture to Virginia Agricultural and Mechanical College and Polytechnic Institute (now Virginia Tech) in 1914, Agnew became an employee of the university.

In 1919, Agnew became president of the Virginia Federation of Business and Professional Women's Clubs. Two years later, she became a member of the national YWCA finance department. From 1927 to 1931, she served as editor of the women's department at Southern Planter magazine and from 1933 to 1943 as head of New Deal relief activities for Virginia women. Ella Agnew retired in 1943 and died on February 5, 1958. She was buried in Sunset Hill Cemetery, Burkeville, Virginia. At Virginia Tech, Agnew was the first woman to receive a certificate of merit (1926) and the first to have a building (Agnew Hall) named in her honor (1949).