<p>External plasticization is an effective strategy to enhance the processability and flexibility of polylactic acid (PLA). The success of this approach largely depends on the miscibility and diffusion of the plasticizer within the polymer matrix, ensuring long-term material stability. Conventional plasticizers, often phthalate-based and synthetically derived, pose environmental and health risks due to their carcinogenic nature and tendency to leach at ambient temperatures. In this study, ricinoleic acid–based esters were synthesized as bio-based alternatives for PLA plasticization. Two esters icinoleic ester (RE) and benzoic ricinoleic ester (BRE) were synthesized using ricinoleic acid, benzoic acid, and trimethylolpropane. The extent of esterification was verified by acid value analysis, FTIR spectroscopy, and ¹H NMR. PLA was plasticized with varying loadings of RE and BRE, and the resulting materials were characterized using DSC, TGA, FTIR, UTM, and rheological analysis. Both plasticizers exhibited thermal stability at PLA processing temperatures, with BRE showing superior miscibility and plasticization efficiency. A loading of 10 phr was found optimal, resulting in significant Tg reduction and improved flexibility. The findings suggest that BRE, in particular, offers a promising bio-based plasticizer for enhancing the performance of PLA without compromising its inherent properties.</p> Graphical abstract <p></p>