In recent years, the penternary nanocrystals synthesized as an alternative to Pt in dye-sensitized solar cells have attracted the attention of researchers due to their many important properties such as low-cost elemental component, high absorption coefficient, optimal optical band gap, high efficiency and environmental stability. Because of these attractive features, a new penternary chalcogenide semiconductor, namely Cu2CoSn(SSe)4 (CCTSSe), have been synthesized by hot-injection technique and its structural, dielectrical and optical dispersion characteristics have been reported. CCTSSe nanostructure films were produced by spin-coating method onto glass substrates. The optical, morphological, compositional and structural properties of this penternary chalcogenide semiconductor was characterized by ultraviolet–visible-near (UV–VIS-NIR) spectroscopy, energy-dispersive spectrometer (EDS), Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The CCTSSe penternary nanostructure has a band gap energy of 1.186 eV, single crystalline, adequate stoichiometric ratio, kesterite phase and 10–20 nm particle sizes which are forming nanospheres. The optical dispersion and dielectric characteristics were investigated based on the reflectance and transmittance spectra measured by spectrophotometer between 200 and 2000 nm. The value of extinction coefficient and refractive index were estimated, and a relation between the optical band gap values and the refractive index values was debated. The values of oscillator energy and dispersion energy were determined by the single oscillator of the Wemple–DiDomenico method. The loss tangent and the dielectric constants were evaluated. The obtained results report the capability of the high-efficiency and low-cost CCTSSe thin films in photonic and photovoltaic applications, especially in dye-sensitized solar cells.