High entropy spinel oxide (HESO) with five or more metal elements randomly distributed in the crystalline oxide lattice, can exhibit unique physical and chemical characteristics. Herein, we present a HESO composed of Ni, Cu, Zn, Co, and Mn as a multi-functional photocatalyst for synchronized photothermal-photodegradation reactions. Experimental evaluation and density functional theory (DFT) calculation analysis reveal that the HESO with optimized quasi-metallic properties affords high solar energy harvest efficiency with an excellent solar evaporation rate of 2.6 kg·m⁻²·h⁻¹ and 83.9% evaporation efficiency under 1 sun irradiation. Simultaneously, the diverse metal ions in the octahedral sites facilitate long-distance charge carrier transfer pathways within HESO, achieving the 94.3% removal of tetracycline (TC) within 20 min via photocatalysis at a concentration of 0.3 g·L⁻¹ assisted by visible-light-driven activation of peroxymonosulfate (PMS). Long-term cycling tests for photothermal-photodegradation demonstrate the reliability and reusability of HESO in practical applications. This finding provides a new perspective to design the multi-functional photothermal photocatalysts for simultaneous photodegradation and clean water production.