<p>This work introduces a newly engineered Al–Zn co-doped BaTiO₃ system that simultaneously exhibits a colossal dielectric permittivity and outstanding photocatalytic performance for multifunctional applications in high-density energy storage and environmental remediation. The photocatalytic activity of pure and Al–Zn co-doped BaTiO₃ ceramics was systematically investigated for the degradation of Rhodamine B (RhB) and malachite green (MG) dyes in aqueous media under natural sunlight irradiation. Both pure and codoped samples crystallize in a single-phase tetragonal perovskite structure without detectable of any secondary phases, confirming structural stability upon codoping. Incorporation of Al and Zn ions induces a significant microstructural refinement, yielding uniformly distributed fine grains. The band structure modulation is achieved through codoping, narrowing the optical band gap from 3.2 to 2.81&#xa0;eV, thereby extending light absorption into a broader spectral range. XPS analysis confirms the presence of Ba²⁺, Ti⁴⁺/Ti³⁺, Al³⁺, and Zn²⁺ oxidation state, along with the formation of oxygen vacancies which play a crucial role in enhancing the charge separation and interfacial activity. Al–Zn codoped composition (BaTi_0.96Al_0.02Zn_0.02O₃) displays a high dielectric permittivity of 21,395 at 100&#xa0;Hz with stable low-frequency behavior, highlighting its potential for advanced energy storage applications. Besides, BaTi_0.96Al_0.02Zn_0.02O₃ catalyst demonstrates a rapid and efficient photocatalytic degradation of &gt; 97% for both RhB and MG within 30–35&#xa0;min, along with excellent reusability and structural stability. This study proves that the strategic of Al–Zn codoping into BaTiO₃ effectively integrates defect engineering, band structure tuning, and microstructural control to achieve a high dielectric constant and environmental remediation performance within a single material platform.</p> Graphical Abstract <p></p>