Considering the needs of designing suitable food packaging that is able to decrease food losses while reducing the overall environmental impact of the food/packaging system, full biocomposites, i.e., both biodegradable and bio-sourced, are becoming serious candidates for food packaging applications. This article aims at reviewing the knowledge about the functional properties of vegetal fibers-based biocomposites, by considering the specific stakes relative to the food packaging application, i.e., the targeted functional properties, including mechanical properties and mass transfer properties (especially the permeability toward O2, CO2, and water vapor), the processability of materials using conventional equipments, the economical competitiveness, and the food safety. The first part summarizes the main characteristics of the constituents, i.e., matrices and fillers, and the processing routes to prepare biocomposites. In the second part, the ways to better understand and control the mass transfer properties in biocomposites will be deciphered by reminding the role of mass transfers in the food/packaging system and by focusing on how mass transfer properties are impacted by the material structure and mechanical properties. Food safety aspects will also be considered, by highlighting the possible undesirable migration from biocomposites toward food. This review will conclude on the main bottlenecks that should be resolved in order to make the use of biocomposites more viable for food packaging applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42528.