The institution that is now William Carey University had its earliest origins in Poplarville, Mississippi, when the noted educator W. I. Thames opened Pearl River Boarding School in 1892. As did many institutions of its day, Pearl River Boarding School offered “elementary, preparatory and some college work. Operating for decades as Mississippi Woman's College, the institution was renamed in honor of the founder of modern missions in 1954 when the school became coeducational.
William Carey University is located on three campuses in Hattiesburg, Mississippi, Biloxi, Mississippi, and Baton Rouge, Louisiana.
- The main campus is in Hattiesburg and is set on 170 acres.
- The Tradition Campus is located in Biloxi on Highway 67 in the Tradition community.
- The Baton Rouge campus is located within Baton Rouge General Hospital.