AbstractGreat environmental and economic benefits can be achieved by utilizing the agricultural residue corn stover (CS) to prepare the biodegradable poly(butylene adipate‐co‐terephthalate) (PBAT) composites. However, CS contains polarized hydroxyl groups from its main component cellulose, thus leading to its poor wetting by hydrophobic PBAT. It is of great significance to promote the compatibility between CS and PBAT for the improvement of interfacial interactions and composite performance, but the compatibilizer modified CS/PBAT biocomposites have been rarely mentioned until now. In this study, polyethylene glycol (PEG), glycidyl methacylate (GMA), and ethylene vinyl alcohol copolymer (EVOH) were chosen to investigate the compatibilizer effect on the morphology, microstructure, thermal properties, mechanical strength, and water absorption capacity of the biodegradable CS/PBAT composites. The results reveal that the incorporated compatibilizers obviously improve the interface adhesion between CS and PBAT by reducing the hydrophilicity of CS surface. The enhanced interfacial bonding interactions effectively promote the crystallinity and mechanical strength of the CS/PBAT composites, but the initial degradation temperature and hydrophilicity of compatibilizers themselves also remarkably influence the composites’ thermostability and water absorption.Highlights The agricultural residue corn stover (CS) was used to reinforce PBAT. Effects of three different compatibilizers on the composites were studied. Compatibilizer improves the interface adhesion between CS and PBAT. Compatibilizer promotes crystallinity and mechanical strength of composites. The stability and hydrophilicity of compatibilizer affect those of composite.