This article describes a photoredox-enabled functionalized carbon-atom insertion reaction into indene, leading to the synthesis of 2-substituted naphthalenes. The key to this transformation is the use of masked carbonyl radical species, specifically α-iodonium diazo compounds, which facilitate the insertion of various functional groups, including trifluoromethyl, ester, phosphate ester, sulfonate ester, sulfone, nitrile, amide, aryl ketone, and aliphatic ketone fragments. The reaction is mild, operationally simple, and exhibits broad functional group tolerance. Mechanistic studies, including UV-Vis spectroscopy, Stern-Volmer quenching, cyclic voltammetry, and DFT calculations, suggest a radical chain mechanism involving a single-electron transfer from the photocatalyst to the α-iodonium diazo compound, followed by radical addition to indene and subsequent rearrangement to form the final product. This method provides a versatile tool for skeletal editing and the synthesis of complex molecules, particularly those with pharmaceutical relevance.This article describes a photoredox-enabled functionalized carbon-atom insertion reaction into indene, leading to the synthesis of 2-substituted naphthalenes. The key to this transformation is the use of masked carbonyl radical species, specifically α-iodonium diazo compounds, which facilitate the insertion of various functional groups, including trifluoromethyl, ester, phosphate ester, sulfonate ester, sulfone, nitrile, amide, aryl ketone, and aliphatic ketone fragments. The reaction is mild, operationally simple, and exhibits broad functional group tolerance. Mechanistic studies, including UV-Vis spectroscopy, Stern-Volmer quenching, cyclic voltammetry, and DFT calculations, suggest a radical chain mechanism involving a single-electron transfer from the photocatalyst to the α-iodonium diazo compound, followed by radical addition to indene and subsequent rearrangement to form the final product. This method provides a versatile tool for skeletal editing and the synthesis of complex molecules, particularly those with pharmaceutical relevance.