Apprenticed to Willis Polk in San Francisco before moving to New York City to become a social architect like Stanford White. He began a commission in Palm Beach, FL, to design a hospital, which was later completed as the Everglades Club (1918). It was designed in a Mediterranean Revival style, which influenced many buildings in the area. He later became a developer, noted for his Spanish Revival buildings and Florida resort architecture. Mizner was the visionary behind the development of Boca Raton, but the Florida land boom ended, and his career never attained the potential.