Here, we propose a p-type copper aluminum oxide (p-CuAlO₂) interlayer for the high breakdown and low leakage current of β-Ga₂O₃ Schottky barrier diodes (SBDs). The XPS and TEM analysis was employed to confirm the surface elemental compositions, chemical states, and microstructural properties of RF sputtered p-CuAlO₂ thin films on β-Ga₂O₃. The electrical and carrier transport properties of Pt/β-Ga₂O₃ SBD and Pt/p-CuAlO₂/β-Ga₂O₃ heterojunction (HJ) were studied by using current-voltage (I–V) and capacitance-voltage (C–V) measurements. In comparison to the SBD, the HJ displayed superior rectifying behavior, lower reverse leakage current, lower on-resistance, and a larger turn-on voltage. Higher barrier height (BH) was attained for the HJ compared to the SBD, which enabled the p-CuAlO₂ interlayer to alter the barrier height. The reverse breakdown voltage of HJ increased by nearly 300 V compared to SBD and reached a maximum of 922 V. The BH values were extracted from the I–V, Hernandez, Cheung's, Mikhelashvili, Norde's, Chot, and surface potential methods found the values are comparable with one another, which indicates their steadiness and validity. The energy distribution profile of the interface state density (N_SS) of the HJ decreases compared to the SBD, which indicates that the p-CuAlO₂ interlayer facilitated the reduction of N_SS of the Pt/β-Ga₂O₃ SBD interface. The forward log(I)-log(V) plot of the SBD and HJ reveals the ohmic nature at low voltage regions and space-charge limited conduction at higher voltage regions. Results reveal that the reverse leakage current conduction mechanism of the SBD and HJ showed that the Poole-Frenkel conduction mechanism is found to be governed in the lower voltage region, whereas the Schottky conduction mechanism is found to be directed in the higher voltage region, respectively. These outcomes point out that the p-CuAlO₂ is a high potential candidate material for forming a heterojunction with β-Ga₂O₃.