We compared bare magnesium oxide NPs synthesized by chemical co-precipitation (Bare MgO) with the biogenic synthesis of magnesium oxide NPs (g-MgO) that were fabricated using variant concentrations of datura metel leaf extract (i.e., 10 ml and 20 ml). PXRD, FT-IR, UV-visible spectroscopy, PL, and SEM were performed to investigate the nanoparticles synthesized from Datura metel leaf extraction (DLE). It is evident from the PXRD analysis that these nanoparticles have a diffraction pattern corresponding to cubic MgO and hexagonal Mg(OH)(2 )crystals with crystal sizes of 8.44, 7.93, and 7.85 nm which, decreased with an increase in Datura leaf extraction concentration. Vibrational stretching modes between 450 and 570 cm(- 1) for cubic MgO and hexagonal sites were established by FT-IR, and the band gap estimated by UV-visible spectroscopy was found to be 3.87, 4.02, and 4.21 eV with the rise in DLE concentration, highest luminescence intensity was found at 463, 468 and 473 nm. SEM reviles agglomerated images with nanoflakes structure. The rhodamine B dye was degraded by a percentage of 71.05, 74.35, and 79.67 %, under visible light using these nanoparticles. Additionally, well-diffusion testing was performed against gram-positive and gram-negative bacterial strains (Staphylococcus aureus and Klebsiella pneumonia). These relative results indicated that the naturally synthesized NPs show better results than the reported articles.