The unique solid-solution structure and multi-element compositions of high-entropy alloy nanoparticles (HEA NPs) have garnered substantial attention. Various methods have been developed to prepare a diverse array of HEA NPs using different substrates for support and stabilization. In this study, we present a facile surface-mediated reduction method to prepare HEA NPs (AuAgCuPdPt) decorated germanane (HEA NPs@GeNSs), and employ X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) to characterize their structure, composition, and morphology. Subsequently, we demonstrate that the HEA NPs can be liberated from the surfaces of GeNSs as freestanding systems via straightforward exposure to UV light. We also explore germanium nanoparticles (GeNPs) as an alternative substrate for HEA NP formation/production, given their similarity to germanane and their Ge-H surface. Finally, we extend our investigation to bulk Ge wafers and demonstrate successful deposition of HEA NPs.