<p>Artificial photosynthesis provides an efficient strategy for solar energy storage via water splitting and CO₂ reduction, but it remains a challenge in tuning artificial photosynthesis between these two competing reactions. Herein, we demonstrate photoinduced conversion of monometallic to bimetallic sites in a Fe-Co nitroprusside (FeCo–NP) to steer the reaction path from H₂ evolution to CO₂ reduction. Monometallic Co sites achieve efficient H₂ production with 28.5 mmol g⁻¹ activity and 85.4% selectivity. Photoinduced release of nitrosyl groups from Fe sites generates bimetallic Fe-Co sites, which suppress H₂ evolution and enhance CO₂ reduction, yielding 31.5 mmol g⁻¹ activity and 87.3% selectivity for C1 products. Mechanistic investigations reveal that monometallic Co sites catalyze H₂ evolution via H₂O adsorption and O-H cleavage while bimetallic Fe-Co sites facilitate both H₂O and CO₂ adsorption and subsequent O and C hydrogenation for CO and HCOOH. This work uncovers a strategy to manipulate competing reaction pathways via photoinduced conversion of monometallic to bimetallic sites, which provides unique insights into addressing environmental issues and energy crises.</p>