Precise spatiotemporal control of microbial growth is important for advancing applications in engineering biology [1,2]. Light offers an ideal modality for this purpose due to its non-invasive nature and tuneable precision. While current strategies rely on genetically encoded light-responsive systems, their genetic complexity and limited portability restrict broad application with diverse microbial hosts [3]. Here, we introduce a biocompatible photochemical reaction as a versatile, non-genetic method for light-controlled microbial growth and regulation. We demonstrate that the photo-decaging of protected essential metabolites enable a light-responsive ‘turn-on’ switch for microbial growth and replication that permits fine-tuned temporal control of growth rate and final cell density across microbial domains. Furthermore, this approach enables the orthogonal regulation of microbial populations in co-culture and precise spatial living patterning on solid media. This platform establishes a simple and general strategy for light-responsive microbial control by employing biocompatible chemistry, and expands the toolkit for precise and modular regulation across engineered and unmodified hosts. References: 1. Alter, T. B. & Ebert, B. E. BMC Bioinformatics 20, 447 (2019). 2. Wright, O., Delmans, M., Stan, G.-B. & Ellis, T. ACS Synth Biol 4, 307–316 (2015). 3. Benisch, M., Aoki, S. K. & Khammash, M. Curr Opin Microbiol 77, 102404 (2024).