A microwave assisted hydrothermal method, where the advantages of both microwave and hydrothermal methods are utilized to synthesize complex fluoride KMF3 (M = Zn, Mn, Co, Fe), materials of technological importance, is proposed. The KMF3 metal fluorides synthesized feature nano-sized particles having well-defined cubic morphologies. The proposed synthesis, in contrast to the existing synthesis methods is very rapid, economical, and less complex in nature. The structural, thermal, optical, and chemical properties of synthesized powders are determined by powder X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and diffuse reflectance spectra in the UV-VIS range.