AbstractArtificial photosynthesis employing solar energy is one of the best means of reaching a sustainable energy cycle, in which water is oxidized to oxygen and supplies electrons for fuel generation. The development of suitable oxygen evolution materials driven by sunlight is hence the most challenging research topic in the field of photocatalysis. Herein, photocatalytic O2 production from water at a rate of 22.6 μmol h−1 was performed by using a pyrene‐based organic molecule constructed through the Ullmann coupling reaction. Its significantly improved light‐harvesting ability and notably accelerated separation and transfer of photogenerated charges enhanced the O2 evolution efficiency. This study highlights the structural design of organic molecules applied to photocatalytic water splitting.