A novel route was proposed for the synthesis of transparent dispersions of monodispersed zinc oxide (ZnO) nanoparticles via a high-gravity reactive precipitation combined with "inorganic-organic successive layer coating" method. The as-prepared nanodispersion had a uniform particle size of about 4 nm, high stability of over 12 months, and still remained transparent at ultrahigh solid content of 60 wt %. Highly transparent polylactide (PLA)/ZnO and PLA/ZnO/cesium doped tungsten oxide CsxWO3 nanocomposite films were further fabricated by a simple solution mixing method. Because of the uniform dispersion of nanoparticles, PLA/ZnO films could maintain the same visible transmittance as pure PLA film even when ZnO content reached 60 parts per hundred of PLA resin by weight (phr). Furthermore, the films could shield almost 100% ultraviolet radiation at ZnO content of up to 5 phr, thereby realizing good antiaging property. Besides their excellent transparency and UV-shielding property, PLA/ZnO/CsxWO3 films could also block 90% near-infrared radiation, thereby displaying excellent heat insulation ability. It could be envisioned that this nanocomposite would have great potential in many applications such as smart windows, agricultural film, fabrics, etc.