This paper aims at an interdisciplinary study of the history of local Daoism in early Republican Canton. Through a case study of the ritual specialists of Nahm-mouh Daoist masters during the late Qing and early Republican period, it focuses on how Cantonese Daoism tried to adapt to the changing political circumstances of the early Republican period. According to the findings of an official investigation on the “Occupations of Divination, Astrology, Physiognomy and Palmistry, Sorcery and Geomancy” by the Nationalist government in Canton in 1933, there were more than 276 Nahm-mouh Daoist halls spread all over Canton at that time. They provided almost all the Daoist ritual services for the Cantonese people in the city. In the campaign against superstition and popular religion called the Fengsu Gaige (Reform of Customs), the self-styled progressive Nationalist government in Canton condemned the Nahm-mouh Daoist masters as sorcerers. In 1928 and again in 1936, the government twice ordered the banning of all Nahm-mouh ritual services and closed all Daoist Halls. In order to effectively abolish Nahm–mouh ritual activities in Canton, the city bureau of social affairs and the police force jointly investigated the Nahm-mouh Daoist masters in the city and duly produced a comprehensive report including the names and total number of Nahm-mouh Daoist masters, their home villages and updated addresses of their Daoist Halls. Based upon the 1933 report presently kept in the City Library of Zhongshan in Canton, this paper attempts to reconstruct the history of Nahm-mouh Daoist masters, the geographical distribution of their Daoist Halls, and their ritual activities in early Republican Canton. Due to the Nationalist government’s antireligious policy of destroying Nahm-mouh Daoist ritual activities in public, the Nahm-mouh Daoist halls could not survive intact to 1949. In the wake of the Second World War, some Cantonese Nahm-mouh Daoist masters fled from the war-affected city and moved to Hong Kong in 1940 and restarted their ritual services there. A union of the “Nahm-mouh Daoist Masters Living Abroad in Hong Kong” was organized and found by most of them in 1947, which was to have a great influence on the later development of Daoist ritual traditions in Hong Kong.