In this work, a method for the measurement of one-dimensional (1D) UV radiation dose is described. It comprises a new tablet dosimeter that measures the dose using reflectance spectrophotometry. The tablet dosimeter elaborated is a solid structure with a cylindrical form and has been manufactured with polycaprolactone (PCL) doped with a representative of tetrazolium salts: 2,3,5−triphenyltetrazolium chloride (TTC). The PCL used makes the dosimeter biodegradable and therefore proecological. The TTC dopant is distributed uniformly in the whole PCL tablet, and the whole tablet changes color to red under UVC irradiation. The intensity of this color increases if the PCL–TTC tablet absorbs higher doses. The color of the tablet is stable for at least 30 days after irradiation. It is proposed that the PCL-TTC tablet be used for measurement with reflectance spectrophotometry in order to determine the reflectance of light versus the absorbed dose in a fast and easy manner. On this basis, the PCL-TTC tablet could be characterized by providing information on its dose range, which amounted to 0–2 J/cm2. Moreover, other parameters were derived, such as dose sensitivity, quasilinear dose range, and dose threshold. The morphology of the tablets studied using scanning electron microscopy revealed their high porosity, which however did not influence the reflectance measurements with the aid of the chosen instrument. UVC irradiation at a dose (15 J/cm2) much above the PCL-TTC tablets’ dose range did not alter the morphology of the tablets. The PCL-TTC tablet read with reflectance spectrophotometry is shown to be a promising and fast method for 1D UV dose measurements.