The Paiter Suruí people possess extensive traditional knowledge about culturally significant plants, particularly the babassu palm (Attalea speciosa Mart.). This study catalogs the diverse uses of babassu and evaluates its status as a Cultural Keystone Species (CKS) for the Paiter Suruí. Ethnobotanical methodologies were employed to gather and analyze data from Joaquim village, corroborating existing literature and expanding the understanding of babassu’s cultural importance. Our findings reveal 27 distinct uses of babassu, categorized into seven main categories and ten subcategories, with 52% of these uses still actively practiced and 48% no longer practiced. Babassu is utilized for construction (e.g., thatching homes), crafting utensils (e.g., basketry), and food (e.g., mesocarp flour and insects). However, traditional medicinal uses have largely been abandoned. The continued use of babassu for food and construction underscores its irreplaceable role in the daily lives and cultural identity of the Paiter Suruí. These practices, combined with diverse terminologies in their language and the symbolic significance of babassu in myths, support its designation as a CKS. This study contributes to the broader discourse on biocultural conservation and the importance of integrating Indigenous perspectives into sustainable management practices.