Chemoselective cysteine modification is pivotal for chemical biology and drug discovery. While photochemical strategies offer spatiotemporal control, most current methods rely on exogenous catalysts, complicating purification processes. Furthermore, the structural diversity of accessible conjugates remains limited. Here, we report an additive/catalyst-free, visible-light-driven platform for divergent cysteine modification via indole isocyanide photochemistry. This strategy eliminates the need for external additives or photocatalysts, ensuring excellent biocompatibility and operational simplicity. A key practical advantage of this method is its compatibility with both solution-phase and solid-phase reaction systems, offering unmatched flexibility for diverse experimental setups. By leveraging the tunable structure of indole isocyanides, this photoreaction readily generates a diverse array of indole-fused or indole-spiro aza-cycles at cysteine residues. We demonstrate broad utility of this method, ranging from