Macroporous resin NKA-9 was used as the support for the immobilization of lipase from the fungus Rhizomucor miehei (RML). The resin-supported RML (RML@NKA-9) was then used in the enzymatic deacidification of high-acid soybean oil with an oleic acid content of 25% for diacylglycerol (DAG) production. Structural characterization of the resin before and after RML loading using SEM and XPS revealed that RML had been successfully immobilized onto NKA-9. The optimized reaction conditions for enzymatic deacidification and DAG production were as follows: reaction temperature, 50°C; amount of glycerol, 8 wt% of the high-acid oil; and amount of RML@NKA-9, 3 wt% of the high-acid oil. Under these conditions, equilibrium was reached after 8 h of reaction, DAG content of 58.95% was achieved, and free fatty acid (FFA) content was reduced to 1.50%. Subsequently, the reusability of RML@NKA-9 was evaluated. Results indicated almost no activity loss after four cycles of use, and the retention of 49.10% of initial activity after six cycles of use. The RML@NKA-9 prepared in this study enabled the effective removal of FFAs from high-acid oil, achieved the production of considerable DAG content, and demonstrated a certain degree of reusability. Therefore, RML@NKA-9 possesses promising prospects for applications in oil processing.