n-Type Zr-Ni-Sn thermoelectric thin films with thickness of 60 nm to 400 nm were deposited by radiofrequency magnetron sputtering. The microstructure of the Zr-Ni-Sn thin films was examined by x-ray diffractometry and high-resolution transmission electron microscopy, revealing an amorphous microstructure. The thermal conductivity of the amorphous films was measured by the ultrafast laser pump-probe thermoreflectance technique, revealing values of 1.4 W m-1 K-1 to 2.2 W m-1 K-1, smaller than that of bulk material because of the amorphous microstructure of the films. The effects of the sputtering power on the composition, Seebeck coefficient, and electrical conductivity of the films were investigated. The largest Seebeck coefficient and power factor were achieved at 393 K, being -112.0 μV K-1 and 2.66 mW K-2 m-1, respectively. The low thermal conductivity and high power factor indicate that amorphous Zr-Ni-Sn thin films could be a promising material for use in thermoelectric microdevices.