Mazuism, or the worship of the Chinese sea goddess Mazu, was once a spiritual anchor for Chinese people who settled in Southeast Asia, and played a crucial role in the establishment of solidarity among them. It was not merely one of many folk religions that originated from China, but a very important source of knowledge about the underlying culture of the Chinese communities in Southeast Asia. In this study, the main discussion is focused on the origins, diverse aspects, and propagation of Mazuism in Southeast Asia, a topic rarely handled among scholars studying the worship of Mazu in China and its neighboring countries. The first chapter of the essay deals with various aspects of Mazuism and the shrines of Mazu in Southeast Asia. Studies show that the buildings used as shrines and assembly halls of Mazu worshipers are connected with the structure and style of the Chinese architecture of Guangdong and Fujian provinces in mainland China. According to a recent discovery, many of the Mazuist shrines across Southeast Asia were also devoted to local guardian deities, which suggests that Mazuism in Southeast Asia was originally a folk religion that prospered among Chinese communities across the region, but then changed and evolved through the process of localization based on a syncretization of some of the world’s major religions and local popular beliefs. In the second chapter, the main discussion focuses on the origins of Mazuism in Southeast Asia, revealing that the early Chinese communities that devoted themselves to the worship of Mazu and her shrines in this area originated from two provinces, Guangdong and Fujian, in mainland China. Fujian, the birthplace of Mazuism, and its neighboring province, Guangdong, were home to the most ardent worshipers of the sea goddess. As such, it is conjectured that Mazuism was introduced to and spread throughout Southeast Asia due to the inflow of Chinese immigrants from Fujian and Guangdong during the Ming and Qing periods. The discussion in the final chapter focuses on the background to the large-scale migration of Chinese people from Fujian and Guangdong to Southeast Asia and the relationship between the maritime activities in the region and Mazuism. People of Fujian and Guangdong who were involved in fishing and trading began to worship Mazu as their sea guardian during the Northern Song period. In the subsequent Ming and Qing periods, the worship of Mazu became increasingly ardent and widespread among the Chinese migrating to Southeast Asia. These Chinese migrants believed that worship of the sea goddess helped them to navigate safely on the seas, and carried statues of Mazu with them when they sailed to Southeast Asia in an effort to uphold their faith. The study also shows that in some areas of Southeast Asia Mazu ultimately came to be worshiped not as a guardian goddess of seafarers but as an all-powerful deity.