Integrating photoelectrochemical biomass upgrading and hydrogen production is a promising route for sustainable energy conversion and chemical production. In this presentation, we report bismuth vanadate (BVO) photoanodes modified with cobalt phosphate (CoPi) to facilitate TEMPO-mediated oxidation of 5-(hydroxymethyl)furfural (HMF). Tuning CoPi electrodeposition time enabled the preference for TEMPO oxidation or oxygen evolution reaction (OER) to be tailored. Photoanodes optimized for TEMPO oxidation decreased the required potential by 500 mV and increased charge injection efficiency by seven-fold compared to BVO, while also suppressing undesired OER. Using transient photocurrent measurements, we revealed that the back-reduction of oxidized TEMPO was detrimental to BVO photocurrents. We propose that the role of CoPi for enhancing TEMPO oxidation photocurrents was to suppress the back-reduction, rather than to directly accelerate TEMPO oxidation. TEMPO-mediated oxidation of HMF with BVO/CoPi achieved 88% yield to 2,5-furandicarboxylic acid (FDCA), an important biobased polymer precursor, under mild conditions. In contrast, <1% FDCA was generated with BVO under identical conditions. These findings will promote the development of more efficient photoelectrochemical devices for biomass upgrading and renewable energy conversion in the future.