Culturally based mangrove forest ecosystem management is crucial because the Metinaro community places significant value on cultural practices, including rituals designed to communicate directly with ancestral spirits. The community believes that ancestral spirits are capable of protecting biodiversity, non-biological resources, and the Metinaro community as a whole. Such protection, particularly in relation to the physical, biological, and economic functions of mangrove forests, is essential for coastal communities. This research aimed to examine the process of culturally based mangrove forest ecosystem management in Metinaro, Timor-Leste. Data were collected through interviews with traditional elders and fishing group leaders, while descriptive analysis was used to analyze the interview and survey results. The mangrove forest ecosystem management process was carried out collaboratively by local communities and traditional elders, as both groups were bound by customary rules considered sacred law. These customary practices began with a ritual led by a traditional healer in the form of direct communication with ancestral spirits to request permission and seek guidance for mangrove forest management activities. This ritual was generally performed at the traditional house of worship, with offerings including pigs and goats, as well as betel and areca nuts, presented to honor ancestral spirits. The research findings showed that all living organisms, including the diversity of species within the mangrove forest ecosystem and other wildlife such as white monkeys, broad-winged bats, parrots, snakes, cockatoos (yellow-crested and white-crested), storks, fish, crabs, and other species, have remained well preserved and sustainable to date.