Display omitted •Multifunctional vanillin-based porphyrin (VPR) was designed and synthesized.•PLA/VPR biocomposites exhibited highly enhanced toughness.•PLA/VPR biocomposites showed excellent UV-resistance properties.•PLA/VPR biocomposites presented great self-extinguishing performance. To achieve high-performance polylactic acid (PLA) composites, the exploitation of multifunctional biomass additives derived from renewable resources are highly demanded. Herein, a vanillin-based porphyrin (VPR) was designed and synthesized to impart PLA with enhanced mechanical, anti-UV, and flame retardant properties. Multiple intermolecular interactions between VPR and PLA enabled significant toughening of the PLA/VPR biocomposites compared to PLA itself. The elongation at break and impact strength for PLA/3VPR were improved by 88.2 % and 104.2 %, respectively, without influence on their tensile strength. Furthermore, the PLA/VPR biocomposites exhibited improved anti-UV performance with only 1.5 % and 8.6 % decrease of the strength and elongation at break respectively after UV aging. More importantly, incorporation of only 3 wt% VPR loading within the PLA/3VPR composite allowed for excellent self-extinguishing with a UL-94 V-0 level, greatly improving the versatility of PLA composites. We envision that such bio-based PLA/VPR materials with multifunctional features will extensively broaden the usable range of PLA composites.