The photoinduced chiroptical properties of an optically active methacrylic polymer bearing in the side-chain a conjugated trans-azoaromatic chromophore linked to the main chain through a chiral cyclic pyrrolidine moiety of one prevailing absolute configuration have been investigated. The polymeric film is characterized by a strong optical activity that can be amplified and reversibly modulated by irradiation with circularly polarized (CP) light at 488 nm. A remarkable modification of the shape of the circular dichroism (CD) spectrum after the initial irradiation steps is observed, with an amplification of the CD signal upon increasing the total irradiation fluence. The most important results are connected with the handedness of the CP radiation: left circularly polarized (CP-L) light is able to reverse the relative sign of the CD spectra, whereas by pumping with right circularly polarized (CP-R) radiation, it is possible to recover the original shape of the signal. This well reproducible and reversible effect suggests the possibility to use the investigated material for chiroptical switching.