After attending the Classical High School in Providence, Rhode Island, Walker pursued his study of architecture at the Massachusetts Institute of Technology, Cambridge, from which he graduated in 1911. In 1916 he received M.I.T.'s Rotch Travelling Scholarship. During World War I he served as lieutenant in the camoflage unit of the Army Corps of Engineer.
In 1919 Walker joined the architectural firm McKenzie, Voorhees & Gemlin in New York and over the following decade won recognition as a leading proponent of the Art Deco style in architecture. During this period he designed the Barclay-Vesey Telephone Building and the Irving Trust Building in Manhattan.
In the 1930s Walker became involved in designing numerous laboratories and research centers in the northeast and middle west; by 1939 the firm had been re-named Voorhees, Walker, Foley & Smith. He designed a number of corporation pavilions at the New York World's Fair of 1939, including those for General Electric, the American Telephone and Telegraph Company, and the Equitable Life Assurance Corporation.
His influence on the architecture of the nation's capital, and its embassies was substantial. In the post World War II period, Walker served on the commission established by United States Department of State to improve the quality of its embassy structures; in 1959 he was appointed by President Eisenhower to the Fine Arts Commission, which has authority over planning and construction in Washington, D. C.; and in 1963 he was appointed to the Pennsylvania Avenue Advisory Council, charged by President Kennedy to redesign America's primary ceremonial boulevard.
The first chancellor and a past president of the American Institute of Architects, in 1957 the AIA selected him to receive its Centennial Medal. Walker remained active as a practicing architect throughout his life, which extended well into the period of dominence of the severe, geometric buildings in the post World War II period. He was an outspoken critic of the International School, equating its use of unadorned steel and glass with "prison" architecture.
