Various concentrations (2 and 4 wt%) of Samarium (Sm3+) with a fixed amount (3 wt%) of polyvinylpyrrolidone (PVP) doped magnesium oxide (MgO) nanostructures (NSs) were synthesized via facile co-precipitation route. Trivalent dopant (Sm3+) and PVP narrowed the effective band gap of MgO and, controlled the recombination dynamics of the electron-hole pair and stabilized the nanostructures. This innovative treatment aimed to harness the potential ability of MgO to target bacterial cells and eliminate notorious dyes from wastewater. Advanced analytical (EDS and elemental mapping), crystallographic (XRD, SAED, FESEM, TEM and HR-TEM), and optical (UV–Vis and Raman) techniques were operated to probe their exclusive properties. The Sm/PVP-doped MgO displayed a pronounced catalytic activity against RhB dye in an acidic medium (96.42 %). Moreover, antibacterial activity was investigated using an agar well diffusion approach. At a high dosage, the % efficacy of pure and doped nanostructures against MDR S. aureus was 55.05, 65.64, 30.06 and 46.01, respectively. In silico docking investigation indicated that Sm/PVP-doped MgO NSs could inhibit DNA gyrase enzyme in S. aureus.