High-Level Radioactive Waste (HLW) is primarily generated during nuclear power production, consisting mainly of spent nuclear fuel and processed radioactive liquids. The environmental and health risks associated with these wastes necessitate effective solidification technologies for their stabilization and isolation. Hollandite with the general formula A2B8O16, a complex oxide mineral with a tetragonal crystal structure, can incorporate various metal ions, including cesium (Cs), curium (Cm), and plutonium (Pu), within its lattice. Its structural stability under high radiation exposure and elevated temperatures makes it a promising candidate material for HLW solidification. This study employed density functional theory (DFT) calculations to investigate titanate-based hollandite, specifically examining its capacity to immobilize Cs radionuclides within its crystallographic z-axis tunnels. The research focused on analyzing how oxygen vacancy concentration affects the structural stability of BaxCsy (MzTi8-z)O16 hollandite, where M represents trivalent actinides (Cm3⁺, Am3⁺, and Pu3⁺). Results indicate that B-site cation variation significantly influences both Cs loading capacity and hollandite structural stability, as evidenced by calculated formation energies. DFT analyses of vacancy formation energies and enthalpies revealed that increasing oxygen vacancy concentration substantially decreases structural stability. The impact of oxygen vacancies on structural stability varies depending on their location. The presence of oxygen vacancies exerts a more significant destabilizing effect on Ba end-member hollandites when both radioactive and actinide elements are simultaneously present on tetracoordinated oxygen atoms. These vacancies potentially compromise the waste form's long-term integrity, risking Cs release and environmental contamination. This study emphasizes the importance of controlling oxygen stoichiometry and minimizing vacancy formation during synthesis to ensure effective Cs immobilization in nuclear waste management. These findings advance the optimization of experimental synthesis protocols and waste form design, contributing to enhanced durability in geological repository conditions.