Ethnomycology studies how people, particularly indigenous cultures, engage with fungi, including their use for food, medicine, crafts, and cultural rituals and beliefs. This field investigates the traditional knowledge that indigenous cultures have accumulated and passed down over generations, including their distinct methods of identifying, using, and appreciating various fungi. Southeast Asia has over 123 million indigenous people and, therefore, is a rich source of traditional knowledge on fungi, with abundant macrofungi used in culinary, medicine, and cultural rituals including ancient records of using mushrooms as psychedelics. This chapter examines the major ethnomycological studies undertaken in Southeast Asia, emphasizing how indigenous knowledge adds to our understanding of fungi and delving into its culinary, cultural, traditional, and medicinal importance. We propose practical ways to encourage greater global research on ethnomycology.