Abstract A new approach for ionic liquid-based enzymatic hydrolysis in situ trans-resveratrol extraction (ILEHE) from tree peony seed oil extracted residues is presented, in which enzymatic hydrolysis is used in an ionic liquid aqueous medium to enhance the trans-resveratrol yield. Various factors of the ILEHE procedure, including the variety and concentration of enzyme, type and concentration of ionic liquid, liquid–solid ratio and pH of the solution system, and ILEHE temperature and time, were investigated by single-factor experiments, response surface methodology, and first-order kinetic models. A satisfactory yield of trans-resveratrol (5.48 ± 0.14 μmol/g) was obtained by the novel developed approach compared with other conventional techniques. Scanning electronic microscopy of the samples indicated that tree peony seed treated by mixed cellulase and pectinase (1/1, w/w) enzymes in an ionic liquid led to more efficient extraction by reducing mass transfer barrier. The proposed ILEHE method was validated by stability, repeatability, and recovery experiments and shows promising prospects in the extraction and hydrolysis aspects, for enhancing efficiency of target components in natural products.