<p><i>Mandai</i> is a traditional fermented food derived from the inner peel (mesocarp) of the cempedak fruit (<i>Artocarpus champeden</i>), deeply rooted in the culinary traditions of the Banjar ethnic group in South Borneo, Indonesia. Despite its cultural importance and distinctive sensory attributes, <i>mandai</i> has received limited scholarly attention, particularly with respect to its microbial ecology, functional properties, and the potential of controlled fermentation for product development. To date, no comprehensive review has integrated ethnographic perspectives with scientific insights to capture both the cultural significance and the biotechnological potential of <i>mandai</i>. This narrative review addresses this gap by synthesizing current knowledge on <i>mandai</i>’s historical origins, ethnographic perspectives, fermentation methods, microbial diversity, nutritional characteristics, and functional properties, such as antioxidant activity and the role of lactic acid bacteria. Furthermore, it highlights recent advances in starter-induced fermentation as strategies to enhance product safety, consistency, and quality. By articulating an integrative perspective that bridges food science and indigenous knowledge, this review underscores the novelty of <i>mandai</i> as both a cultural heritage food and a promising candidate for future functional food innovation.</p>