The development of efficient and stable catalysts with high mass activity is crucial for acidic oxygen evolution reaction (OER). In this study, CeO₂-Ir heterojunctions supported on carbon nanotubes (CeO₂-Ir/CNTs) are synthesized using a solvothermal method based on the heterostructure strategy. CeO₂-Ir/CNTs demonstrate remarkable effectiveness as catalysts for acidic OER, achieving 10.0 mA cm⁻² at a low overpotential of only 262.9 mV and maintaining stability over 60.0 h. Notably, despite using an Ir dosage 15.3 times lower than that of c-IrO₂, CeO₂-Ir/CNTs exhibit a very high mass activity (2542.3 A g_Ir⁻¹@1.53 V), which is 58.8 times higher than that of c-IrO₂. When applied to acidic water electrolyzes, CeO₂-Ir/CNTs display a prosperous potential for application as anodic catalysts. X-ray photoelectron spectrometer (XPS) analysis reveals that the chemical environment of Ir nanoparticles (NP) can be effectively modulated through coupling with CeO₂. This modulation is believed to be the key factor contributing to the excellent OER catalytic activity and stability observed in CeO₂-Ir/CNTs.