<p>The rapidly growing demand for intrinsically safe, high-energy-density lithium-ion batteries has intensified the pursuit of advanced solid-state electrolytes as viable replacements for conventional liquid systems. Among the leading contenders, lithium aluminum titanium phosphate (Li_1+XAl_XTi_2−X(PO₄)₃)-incorporated composite polymer electrolytes (CPEs) have gained remarkable attention because they unite the high ionic conductivity of NASICON-type LATP ceramics with the mechanical flexibility, processing versatility, and superior interfacial contact offered by polymer matrices. This review delivers a comprehensive evaluation of the structure–property relationships that regulate lithium-ion transport, mechanical durability, thermal robustness, and electrochemical behavior in LATP-based CPEs. The accumulated evidence strongly positions LATP-integrated composite polymer electrolytes as one of the most promising solid-state electrolyte technologies for next-generation lithium-ion batteries. These systems are capable of simultaneously delivering high ionic conductivity (~ 10^–3 S cm⁻¹), exceptional long-term cyclability (&gt; 1000 cycles), high-capacity retention (&gt; 90%), and wide compatibility with various cathode materials, underscoring their significant practical potential. Future advancements should prioritize nanoscale engineering of LATP surfaces, scalable and economically viable fabrication processes, and stable interfacial integration with lithium metal anodes to accelerate the deployment of safe, high-energy-density all-solid-state battery systems.</p> Graphical abstract <p></p>