In line with zero-waste and upcycling strategies, this research seeks to upgrade waste-derived polymethyl methacrylate (PMMA) by undergoing it through catalytic hydrogenation to methyl isobutyrate (Me-iBu) using metallic nickel (Ni) supported on commercial zeolites: HY, H-ZSM-5, and NH4-Beta, H-Beta. The suitability of each zeolite support underwent initial assessment using MMA monomer as the hydrogenation substrate. Operating under 30 bar initial hydrogen pressure (PH2), 250 °C, and a reaction time of 3 h, the NH4-Beta catalyst demonstrated superior hydrogenation performance, accomplishing 87% conversion of MMA and a 57.3 wt% yield of Me-iBu, ascribed to its relatively larger external surface area and pore size. Further optimization, including an increased initial PH2 of 40 bar and prolonged the reaction time to 5 h, led to an enhanced Me-iBu yield of 84.6 wt%. In the course of MMA hydrogenation in a pyrolytic liquid produced from plastic waste PMMA, a high conversion of 99.7% was acquired under conditions (30 bar initial PH2, 250 °C, 5 h). However, the Me-iBu yield did not exceed 37.8 wt%, along with the formation of coupling products (43 wt%) and cyclic byproducts (18 wt%). Increasing the initial PH2 to 40 bar significantly minimized these side reactions, leading to improve the Me-iBu yield to 49 wt%.