The synthesis and confinement of graphitic nanoparticles (carbon dots) in the nanoscale solvent channels of cross-linked lysozyme single crystals is used to prepare novel biohybrid luminescent materials. Co-sequestration of acridine orange within the biohybrid crystals from acidic or neutral solutions yields FRET-mediated phosphors emitting white or green light, respectively. The results offer a route to new types of tuneable multicolour luminescent materials based on microcrystalline host-guest energy-transfer systems.