In response to the growing environmental challenges posed by the improper disposal of plastic food packaging and the urgency to valorize natural resources and agri-food waste, science relentlessly seeks more sustainable approaches, and the use of food waste based-biopolymers represents a promising alternative. Therefore, this work evaluated the use of buriti oil as a potential plasticizing agent in biopolymeric films from different carbohydrate-based matrices, namely, locust bean gum (LBG) and starch (extracted from cassava peel and inner bark), both individually and blended. The films were prepared via casting and characterized in terms of their optical (color and opacity), barrier, and mechanical properties, as well as their biodegradability. The main findings indicated that the incorporation of buriti oil significantly influenced the film characteristics, with different effects depending on the polymeric material's composition. Replacement of glycerol by buriti oil led to increases in luminosity for all films, while color saturation only increased for the pure LGB and blended films. Film opacity increased for the LBG film but decreased for the films containing starch. There was a significant reduction in oxygen and water permeability for the LGB-based film. The materials' biodegradability was positively affected, allowing for prolonged shelf life without compromising their natural decomposition. However, this substitution also led to non-uniformity in LBG/starch films. Furthermore, the complete replacement of glycerol with buriti oil, particularly for films prepared with cassava starch, resulted in a drastic reduction in flexibility and increased fragility, indicating that the oil cannot be employed as the only plasticizer. Nevertheless, the use of buriti oil as an additive or as a partial substitute for glycerol led to interesting results in terms of barrier properties without compromising the film's desired resistance and flexibility, indicating buriti oil as a promising additive for the development of biodegradable films.