Almost all the solar cells created so far have been based on electronic charge. This paper reports a photovoltaic effect based on the spin property of electrons. This spin-based photovoltaic effect was observed on magnetic tunnel junction based molecular spintronics devices (MTJMSD). MTJMSDs were produced by covalently bonding organometallic molecular clusters (OMCs) between the top and bottom ferromagnetic electrodes of Co/NiFe/AlOx/NiFe magnetic tunnel junctions along the exposed side edges. The MTJMSD configuration, which showed the photovoltaic effect, also exhibited OMC induced strong antiferromagnetic coupling (Tyagi et al 2015 Nanotechnology 26 305602) and room temperature current suppression (Tyagi et al 2019 Org. Electron. 64 188-194). Our MTJMSD were fabricated below 100 °C temperature and employed earth-abundant transition metals like nickel and iron. This paper shows that the MTJMSD's photovoltaic effect was susceptible to the magnetic field, temperature, and light intensity. The solar cell efficiency was estimated to be ∼3%. Our MTJMSD approach provides a mass-producible platform for harvesting solar energy and opens a myriad of opportunities to incorporate photogenerated charges for the logic and memory operation in the molecular spintronics devices.