Escalating global environmental concerns have heightened the need for effective chemical production methods employing waste plastics pyrolysis. This study focuses on developing a zeolite catalyst for light olefin production, using 1-dodecene to simulate pyrolysis oil derived from waste polyolefin plastics. Here, various H-ZSM-5 and phosphorus-modified ZSM-5 zeolites with different Si/Al and P/Al ratios were prepared with/without steam treatment, and their physicochemical and catalytic properties for 1-dodecene cracking were studied. Phosphorus introduction decreased the number and strength of acid sites, yet aided in maintaining or generating necessary acid sites for olefin cracking after steaming. Optimal preservation of acid sites and thus, the highest yield of C2–C4 olefins, was attained with a P/Al ratio of 0.7 and Si/Al ratio of 15 after steam treatment. Given its high light olefin yield, hydrothermal stability, and complete regeneration after deactivation, our phosphorus-modified ZSM-5 zeolite is a promising catalyst for waste plastic pyrolysis oil cracking.