Sarmiento studied in various locations in South America, for eighteen months in the office of Oscar Niemeyer, before coming to the United States. He served as the head designer for the Bank Building Corporation of America from 1951 through 1961, after which he founded his own sixty-person Sarmiento Associates office based in St. Louis, Missouri. He retired in 1980.
Sarmiento designed hundreds of banks and other buildings in the postwar years of bank modernization in downtowns, and the construction of new suburban bank towers. His larger work appears as crisp International Style with a visible influence from Niemeyer, perhaps most obvious in his largest project, the 1968 Phoenix Financial Center on Central Avenue in Phoenix, Arizona. The smaller branch banks tend to be more playful, eye-catching, Googie projects.
Sarmiento lived in Santa Monica, California and was still active in the preservation of his buildings until his death in 2013.
- Pioneer Savings Bank Building, on Wilshire Boulevard (3245 Wilshire Boulevard, at northeast corner of New Hampshire St., opposite I. Magnin building), Los Angeles, 1953
- First Security Bank Building, Salt Lake City, 1955 (listed on the National Register of Historic Places)
- Fidelity Federal Savings & Loan Building, California, 1956
- Glendale Federal Savings and Loan, Glendale, California, 1959
- Newport Balboa Savings, Newport Beach, California, 1963 (Demolished)
- Chancery Building, on the grounds of the Cathedral Basilica of St. Louis, circa 1965
- Phoenix Financial Center, Phoenix, Arizona, 1968
- Tucson Western Savings at El Con, Tucson, Arizona 1972
- "Pacific Coast Architecture Database (PCAD)". washington.edu. Retrieved 20 November 2013.
- Nichols, Chris (2 December 2013). "Mid Century Master Architect W.A. Sarmiento Dies At 91". Los Angeles Magazine. Retrieved 3 December 2013.
- Hess, Alan (2004). Googie Redux: Ultramodern Roadside Architecture. Chronicle Books. p. 58.
- National Trust page on the preservation of the First Security Bank in Salt Lake City at the Wayback Machine (archived March 21, 2007)