Williams worked his way through the University of California by teaching art until he became a certified architect in 1915. He continued his studies at the Los Angeles School of Art and Design and the Beaux Arts Institute of Design in New York. Following graduation, Williams searched through the Los Angeles telephone book until he found an architectural firm willing to take on a black draftsman. Williams worked for large architectural firms until he gained sufficient experience in all branches of his profession to open his own office.

Williams's firm took on projects both large and small, working in a variety of architectural styles. Much of his firm's work was residential. Williams not only designed mansions for film stars such as Lon Chaney, Lucille Ball, and Tyrone Power, but also planned thousands of small houses in developments throughout California and Nevada. He wrote about his interest in attractive and comfortable housing for lower-income groups in two publications, Small Homes for Tomorrow and New Homes for Today. Williams served on the Los Angeles City Planning Commission and the city's Municipal Housing Commission. Many of Williams's best-known works were commercial or public. He assisted in the design for the Los Angeles International Airport and the Los Angeles County Courthouse, and was the architect for a number of department stores, hotels, and churches in California and Nevada.