Indanones are key structural motifs in pharmaceuticals and bioactive natural products, making their efficient synthesis a subject of continued interest. Conventional methods typically rely on transition-metal catalysis, prefunctionalized substrates, and multiple redox steps. Herein, we report a photochemical C–H annulation strategy for the direct synthesis of indanones from simple, unmodified aromatic aldehydes and terminal alkynes. The reaction proceeds under 365 nm light using tetrabutylphosphonium decatungstate ([Bu4P]4W10O32, TBPDT) as a hydrogen atom transfer (HAT) photocatalyst. This prefunctionalization-free protocol tolerates a broad range of substrates, eliminates the need for additional redox steps, and expands the toolbox for sustainable indanone synthesis.