Time and frequency resolved emission spectra of a single molecule or a supramolecular complex (SC) placed in the vicinity of a metal nanoparticle (MNP) were computed in the framework of a novel theory. In order to focus on the subwavelength extension of the whole system, the molecule–MNP coupling was restricted to the instantaneous Coulomb-interaction. Its nonperturbative consideration achieved in a density matrix description strongly affected the photon emission but allowed to treat the coupling to transversal photons in perturbation theory. For the single molecule–MNP system a vibrational coordinate was included to describe respective effects of molecular electron-vibrational coupling. When studying an SC interacting with a MNP, intermolecular excitation energy exchange coupling and energy transfer were considered. Respective time and frequency resolved emission spectra were presented. They showed a strong enhancement when compared with the case where the MNP was absent. Furthermore, the emission offered parts of the molecular energy spectra otherwise not visible.