This chapter summarizes recent studies employing colorimetric vesicle-based systems for biomolecular sensing. Vesicular aggregates exhibit an important advantage as a biological sensing platform in that they mimic the cell membrane—the site of molecular docking, ligand–receptor binding, and other important processes that can be exploited as a means of signal generation. Particularly attractive for sensing applications is the use of colour changes visible to the naked eye or detected spectroscopically as the signal transduction mechanism.