This paper highlights Thailand’s distinctive form of Buddhist Modernism through an exploration of religious piety among female sex workers in the city of Chiangmai. The generally accepted key basis of Buddhist Modernism, as depicted by certain Western Buddhist scholars, is interaction and engagement with modernity. More specifically, it is seen as incorporating modern science into the Buddhist worldview, and as regarding meditation as a core practice of ‘true Buddhism’. Crucial components of popular Buddhism, such as magical monks and mystical rituals, are excluded from this depiction of Buddhist Modernism, and even decried as ‘false Buddhism’, despite their canonical basis and long-term acceptance. Using ethnographic methods, this paper argues instead that the result of interactions with modernity by popular Buddhists always includes engagement with and mythologizing of traditional cosmology. That is, rather than solely involving global networks and scientific rationalism, Thai Buddhist Modernism is the product of complex patterns of interaction among local beliefs, mystical practices, and modernity. The purpose of this integration of modern and popular Buddhism in the religious practices of sex workers is to create loving-kindness (metta). Metta, in turn, is held to bring luck and attractiveness to practitioners, allowing them to earn an income to support their impoverished families and live well in modern society, as well as to accumulate good merit (bun) to improve their religious lives.