Metal nanoclusters (NCs) combine the advantages of organic molecules and inorganic nanomaterials, which are promising alternatives in optoelectronic applications. However, for efficient photoluminescence, excited-state compositions of cluster emitter should be tuned through ligand engineering to enhance ligand-centered radiative components and reduce cluster-centered quenching states, which requires delicate and controllable ligand functionalization. In this work, we develop an effective method to augment cluster photoluminescence, which can facilitate the enhancement of phosphorescence emission from several clusters within thin films by leveraging host–guest interactions. The transient absorption spectra and time-resolved emission spectra explicate that energy transfer occurs from the predominant host molecules to the guest clusters by absorption of supplementary photon energy and convering it via the Förster resonance energy transfer (FRET) mechanism. Our discovery paves the way for efficient light harvesting of NCs with simple fabrication using thin films.