Advances in microfl uidic emulsification have enabled the creation of multiphase emulsion drops, which have emerged as promising templates for producing functional microcapsules. However, most previous microencapsulation methods have limitations in terms of capsule stability, functionality, and simplicity of fabrication procedures. Here, we report a simple single-step encapsulation technique that uses an optofl uidic platform to efficiently and precisely encapsulate a specific number of emulsion droplets in photocurable shell droplets. In particular, we show, for the first time, that densely confined core droplets within an oily shell droplet rearrange into a unique configuration that minimizes the interfacial energy, as confirmed here from theory. These structures are then consolidated into multi-cored microcapsules with structural and mechanical stability through in situ photopolymerization of the shell in a continuous mode, which are capable of isolating active materials and releasing them in a controlled manner using well-defined nanohole arrays or nanoscopic silver architectures on thin membranes.