This paper describes a method, based on co-precipitation, for generating small semiconducting polymer dot (Pdot) nanocomposites, which contain either gold or iron oxide nanoparticles within the Pdot matrix. We demonstrate the utility of Pdot-Au nanoparticles (Au-NP-Pdots) in dual-modality imaging in which co-localization of fluorescence from Pdot and scattering from Au was used to identify Au-NP-Pdot probes for downstream single-particle tracking and cellular imaging. We also demonstrate the potential of employing Pdot-FeO(x) nanoparticles (FeO(x)-NP-Pdots) for both sample preparation, where cells tagged with FeO(x)-NP-Pdots were isolated using an external magnet, and cellular imaging and detection, owing to the intense fluorescence from Pdots. The method we present here should be generalizable to the formation of other Pdot nanocomposites for creating the next generation of multi-functional Pdot probes.