<p>The hydrothermal synthesis of zeolite from industrial waste is a cost-effective and environmentally-friendly pathway. In this study, titanium-incorporated ZSM-5 (Ti-ZSM-5) zeolites were synthesized from Ti-bearing blast furnace slag via a seed-assisted template-free method. Silicon-rich residue was first prepared by leaching and precipitation of the slag, followed by hydrothermal reaction to synthesize Ti-ZSM-5 zeolite. The effects of critical parameters (SiO₂/Al₂O₃ and H₂O/SiO₂ molar ratios, hydrothermal temperature and crystallization time) on crystallization behavior were systematically investigated. A high crystalline ZSM-5 zeolite with uniform spindle-like morphology and large surface area (158&#xa0;m²/g) was successfully synthesized under the optimal hydrothermal conditions. Additionally, the physicochemical property and photocatalytic potential of the synthesized zeolites was explored. The results showed that titanium incorporation into the zeolitic framework was approximately 3 <i>wt</i>%, where Ti species existed as framework Ti⁴⁺ and anatase TiO₂, contributing to its intrinsic photocatalytic activity. After TiO₂ loading, the composite photocatalyst achieved nearly 100% degradation efficiency for methyl orange, making this material a promising candidate for applications in catalysis and adsorption fields.</p> Graphical Abstract <p></p>