The name "Namao" originates from the Cree word namêw, meaning "sturgeon," in reference to the lake sturgeon that historically inhabited the nearby Sturgeon River. Settlement in the Namao area began in the late 19th century, with pioneers arriving as early as 1879 to homestead the region amid the broader westward expansion into what was then part of the North-West Territories. By the early 20th century, the community developed key landmarks, including Johnny's Store, constructed in 1902 and recognized as one of Alberta's oldest general stores, which served as a social and economic hub for generations until closing in 2018 and reopening in 2024.
The Post Office opened on May 1, 1892.