This article reports a scalable and roll-to-roll compatible bottom-up self-assembly technology for fabricating macroporous photonic crystal-based polymer films on the reverse side of a photoanode deposited substrate of a dye-sensitized solar cell (DSSC). Both optical measurements and theoretical predications revealed that the as-prepared transparent macroporous films consisting of three-dimensional ordered 200 nm air cavities exhibited anti-ultraviolet (anti-UV) property caused by the Bragg diffraction of ultraviolet radiation from the crystalline lattice of air cavities in the polymer films. The UV-shielding effects on the electrochemical impedance properties and photovoltaic (PV) performance of the UV light illuminated DSSC were studied. The PV properties of the DSSC without the UV-shielding film were decreased significantly as compared to that of the DSSC with the UV-shielding film. The efficiency decay of DSSCs was greatly alleviated by the UV-shielding of such a macroporous polymer film.