A simple technique for observing optically stimulated electron paramagnetic resonance (OSEPR) is proposed and investigated. The versatility and information content of the described technique is demonstrated by the example of the OSEPR spectra of systems that are unpopular for this type of spectroscopy: a crystal with rare-earth ions Nd3+ and a doped semiconductor GaAs. In addition, the OSEPR spectrum of atomic cesium is presented, in which an optical nonlinearity is observed that makes it possible to estimate the Rabi frequency for the relevant optical transition. The effects observed in the described experiments (switching of peaks to dips, light-induced splitting of the OSEPR lines, and the appearance of a spectral feature at the double-Larmor frequency) are interpreted using the model proposed in the theoretical part of the work. The suggested interpretation shows the possibility of using the described OSEPR technique to estimate not only ‘magnetic’ parameters of the model Hamiltonian (g-factors, spin relaxation times), but also the Rabi frequencies characterizing optical transitions.