A cholesteric mixture based on a menthyl-containing copolymer, photosensitive chiral dopant, mesogenic diacrylate, and photoinitiating agent has been prepared. The mixture shows a selective light reflection in the visible light spectral region. The action of UV irradiation (313 or 365 nm) on the planar-oriented films generates the occurrence of two parallel processes: E/Z (i.e., cis-trans) photoisomerization of the chiral dopant and photopolymerization of the diacrylate. The first process leads to the untwisting of the cholesteric helix and shifts the selective light-reflection maximum to the long-wavelength spectral region, whereas the second process leads to the development of a polymer network that fixes the helical supramolecular structure. As a result of a simultaneous occurrence of the two above-mentioned processes. the shift in the selective light-reflection maximum is thermally irreversible, even though the Z/E isomerization of the chiral dopant itself can be reversed by annealing. On irradiation with visible light (>450 nm), the dopant experiences the E/Z isomerization but photopolymerization is absent because the photoinitiator shows no absorption in this spectral region. In this case, the shift in the selective light-reflection maximum can be reversed to its initial value by annealing, whereby the original helix pitch is recovered. The kinetic features of helix untwisting at different temperatures and light wavelengths were studied. The experimental data obtained in this work allow one to conclude that the as-prepared mixture presents a new multifunctional material with "tunable" photo-optical properties and may be used for recording and storage of optical information.