The urgent need for advanced wastewater treatment drives the search for efficient photocatalysts. In this study, we have synthesized a single-phase high-entropy zirconate pyrochlore oxide (Ce0.2Pr0.2Zn0.2Nd0.2Tb0.2)2Zr2O7 via a modified Pechini technique. Several characterization techniques, such as X-ray diffraction, UV–visible spectroscopy, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy, were used to explore the physicochemical features of the synthesized nanoparticles. Cationic dye (methylene blue), anionic dye (Congo red), and Cr(VI) were used to test the photocatalytic capabilities of high-entropy zirconate pyrochlore oxide (Ce₀.₂Pr₀.₂Zn₀.₂Nd₀.₂Tb₀.₂)₂Zr₂O₇ . The photocatalytic findings show that the high-entropy (Ce₀.₂Pr₀.₂Zn₀.₂Nd₀.₂Tb₀.₂)₂Zr₂O₇ zirconate pyrochlore oxide that was made could break down dyes and lower Cr(VI) levels. Radical trap experiments indicate that hydroxyl radicals, superoxide radicals, and holes were responsible for the photocatalytic activity. Furthermore, the placement of the valence band and conduction band decided the photocatalytic reaction kinetics. The prepared photocatalyst also exhibited excellent structural stability and reusability, maintaining its high photocatalytic activity over three consecutive cycles without significant loss of performance. These results underscore the high-entropy pyrochlore’s robust activity, stability, and versatility in treating diverse water contaminants. This study establishes high-entropy zirconate pyrochlore oxide (Ce₀.₂Pr₀.₂Zn₀.₂Nd₀.₂Tb₀.₂)₂Zr₂O₇ as a highly promising and effective photocatalyst for broad-spectrum environmental remediation applications.