The city of Ptolemais was an important religious center during the Graeco-Roman period. The city had its system of cults, directed toward either many deities or the defied members of the royal family. This research aims to study the royal cult in the city during the Graeco-Roman period. It explains the official Greek local cult, centered in the city and addressed to Ptolemy I “Soter" and the Ptolemaic kings in addition to the cult of the Roman emperors. The paper also analyzes the origins of the cult and its development. It illustrates the role of the city to supervise the temples of Soter outside of the city. A historical and analytical methodology is used. The results reveal that there was an official Greek local cult centered in the city, dedicated to Ptolemy I and the other rulers of the Ptolemaic dynasty in Egypt.