Recent advances address the capability to exert externally-triggered photo-control over interfacial and aggregation properties. If a surfactant molecule contains a suitable chromophore, illumination can be used to achieve different physical photo-induced responses. The advantage of this approach is it eliminates the need for composition or temperature changes. Photodestructible surfactant sodium 4-hexylphenylazosulfonate (C6PAS) has been used to drive interesting and dramatic changes in properties of different systems by UV light. Light-induced macroscopic phase separation of micelles and emulsions systems occurs when C6PAS is mixed with an inert noninoic surfactant in the presence of salting-out electrolyte. The initial mixed micelle systems can disperse an insoluble additive marker dye that may be recovered and spatially segregated from the starting heterogeneous aqueous environment by UV light. Other samples, employing photodestructible surfactants in gelatin-based aqueous gels present a novel approach to control rheological and aggregation gel properties with possible applications in systems requiring rheological switches. Light-triggered breakdown of the gelatin-bound photosurfactant aggregates causes dramatic changes in viscosity and aggregation.