In this study, complex BiMn2O5 (BMO) nanoparticles, well known for their applications in photocatalysts, magnetoelectric sensors, actuators, non-volatile information storages, and electrochemical supercapacitors, were synthesized through novel ultrasonication assisted sol–gel synthesis route. The corresponding Rietveld refinement confirms the monophasic nature of composition in Pbam space-group symmetry with orthorhombic structure. The morphological study examines the average grain size determined to be approximately around ∼ 64.50 nm, whereas, EDAX gives the elemental analysis. The vibrational modes of Mn–O and presence of other functional groups have been explored. The coexistence of the multivalency in Mn4+ and Mn3+ valence states, which are associated with the chemical stoichiometry of the synthesized compound is confirmed. The optimization of energy band-gap was attributed to influence the disordered crystal lattice and oxygen vacancies. The interesting Photoluminescence response of BiMn2O5 NPs in visible region indicates strong purple-blue emission under excitation wavelength λex ~ 370 nm and CIE parameters. BMO nanoparticles have been evaluated as a photocatalyst for the decomposition of Rhodamine B dye under visible light illumination because of their low bandgap. In contrast, the pres- ence of smaller nanoparticles and uncompensated spins depict M-H plot shows no saturation at high magnetic field, which manifest non-ferromagnetic correlation. The thermomagnetic study in field-cooled/zero-field-cooled modes also indicates an antiferromagnetic Neel transition at around 41 K. The results obtained from measurements and associated properties of nanoparticles give an insight of BiMn2O5 nanoparticles for possible applications.