Mueang Pran was a city in the southern cities group of Ayutthaya kingdom. In the reign of King Mongkut (Rama IV), the governor of Mueang Pran had full authorised administrative. In 1906 King Chulalongkorn (Rama V) merged Mueang Pran, Mueang Kamnoed Nopphakhun and Mueang Prachuap to a new Mueang Pran Buri and located the city hall at Tambon Ko Lak, now in Amphoe Mueang Prachuap Khiri Khan.

In 1915 to prevent confusion between the cities' names, King Vajiravudh (Rama VI) changed the name of the province from Pran Buri to Prachuap Khiri Khan, as its center was at the same place as the former Mueang Prachuap. This also kept the name of the town and the Pran Buri river together.