<p>Phototrophic bacteria use solar energy to support metabolism and biochemical synthesis and are of increasing interest as systems for industrial chemical manufacture. Biosynthesis using phototrophic bacteria can use various renewable organic and inorganic carbon sources to drive chemical production, without an exogenous supply of refined organic carbon required for traditional dark fermentation used in industrial biotechnology. The potential to use solar energy to convert CO₂ into useful products or upcycle diverse waste streams opens avenues for chemical manufacturing decoupled from fossil resource depletion, potentially with a smaller environmental footprint than other biotechnological routes. Despite this potential, the commercial application of phototrophic bacteria for this purpose is currently limited. In this Review, we discuss the basis for solar chemical bioprocesses in bacteria, emerging tools to engineer phototrophy for bioproduction and give examples of bulk chemical and high-value products synthesized in these species. Finally, we discuss the outlook for this nascent field in the context of chemical synthesis through engineering biology and outline the further progress required to realize the potential of light-powered microbial cell factories for future sustainable industrial synthesis.</p>