Willis Polk's early career included work with McKim, Mead & White, as well as Bernard Maybeck. Polk also worked with Daniel Burnham in Chicago, and then moved to San Francisco to establish and direct Burnham's San Francisco office. Before long, Polk started his own firm and spent many years designing highly regarded California commercial and residential architecture.
Polk was a versatile architect, with particular skill in combining classical styles with environmental harmony. He was regarded for his elegant residential work, mainly in mansions and estates, in the Georgian Revival style for wealthy and prominent San Francisco residents.
In 1917, Polk designed but was not involved in the construction of the single family homes at 831, 837, 843 and 849 Mason Street in the exclusive area of Nob Hill in San Francisco at the intersection with California Street opposite the Mark Hopkins Hotel building. 849 Mason Street was redeveloped into four luxury apartments called Four at the Top in 1983 by the restaurateur and wine maker Pat Kuleto.
Though the well-known dictum, "Make no small plans for they have not the power to stir men's minds." has often been attributed to Daniel Burnham in connection with his work on the McMillan Commission, an exhibit at the National Building Museum in Washington D.C. credits this much quoted sentence to Willis Polk.
Notable Polk buildings 
- Palace of Fine Arts (Polk was the Supervising Architect of the 1915 Exposition)
- Pacific Union Club
- Hallidie Building
- Sunol Water Temple
- Filoli Estate
- The reconstruction of Mission Dolores (1917) which was damaged in the 1906 earthquake
- The Carolands Chateau, following the plans of French architect Ernest Sanson
- Le Petit Trianon
- 86 Sea View, Piedmont CA (for James K. Moffitt)
- 22 Roble Road, Berkeley CA (for Duncan McDuffie)
- 2550 Webster Street, San Francisco CA (for William Bowers Bourn II, which made clinker brick famous)
- Hobart Building, 849 Mas
- Merchants Exchange Building (San Francisco)
- Townhouses at 841-849 Mason Street, San Francisco 
- Mizner, Addison. The Many Mizners. Chicago: Sears, 1932. p. 75
- McCoy, Esther (1960). Five California Architects. New York: Reinhold Publishing Corporation. pp. 37–38. ASIN B000I3Z52W.
- Chronological listing of 65 selected extant architectural works in the Bay Area by Willis Polk (1890-1932)
- On the Edge of the World: Four Architects in San Francisco at the Turn of the Century
- San Francisco: A cultural and literary history