A proficient, eco-friendly, and cost-effective catalyst for remediation of organic contaminants in the environment is a burning issue in recent decades. In the present study, the cobalt doped MnO (Co-MnO) photocatalyst was synthesized via cost-effective and environmentally friendly reverse micelle route. The X-ray diffraction (XRD) results confirmed the synthesis of well-defined cubic-phased MnO and Co-MnO. XRD structural parameters and Williamson-Hall plot of MnO and Co-MnO samples were also explained in detail. Optical band gap analysis revealed an enhanced red-shift of 2.16 eV for Co-MnO photocatalyst as compared to pristine MnO (2.81 eV). The remediation efficiency of pristine MnO and its cobalt doped sample was also was tested using an organic contaminant crystal violet (CV) dye. Excellent synergistic effects of adsorption and photocatalysis at normal conditions, simple degradation mechanism, impressive kinetic investigation, and the low dose utilization proved that the newly synthesized Co-MnO photocatalyst might have commercial applications for environmental applications.