This study investigates pure and Ni-doped Bi2O3 thin film nanorods (5 % and 10 % Ni@Bi2O3) synthesized via a simple wet chemical method at ambient temperature. Powder X-ray diffraction (PXRD) analysis confirmed the formation of monoclinic crystal structures for all samples, with crystallite size decreasing from 44.22 nm (pure Bi2O3) to 37.34 nm (10 % Ni@Bi2O3), calculated using Scherrer’s equation. Tauc’s relation revealed a significant reduction in direct bandgap energy from 2.79 eV (pure Bi2O3) to 2.63 eV (10 % Ni@Bi2O3). Photoluminescence (PL) spectra demonstrated enhanced charge carrier dynamics and reduced recombination rates with Ni doping. HR-SEM and HR-TEM analyses confirmed uniform nanorod morphologies. BET surface area analysis indicated a substantial increase from 25.309 m2/g (pure Bi2O3) to 98.010 m2/g (10 % Ni@Bi2O3), facilitating improved dye adsorption and efficient charge transport. Micro-Raman spectroscopy revealed notable changes in vibrational modes due to increased Ni doping concentration, while XPS results confirmed successful incorporation of Ni3+ ions without secondary phase formation. AFM analysis highlighted increased surface roughness, enhancing optical absorption. Electrochemical impedance spectroscopy (EIS) showed reduced charge-transfer resistance, indicating efficient electron-hole separation. Dye-sensitized solar cells (DSSCs) fabricated using 10 % Ni@Bi2O3 exhibited a notable improvement in power conversion efficiency (PCE), increasing from 0.14 % (pure Bi2O3) to 0.40 %. This enhancement is attributed to increased surface area, conductivity, and improved charge transport properties. Additionally, nonlinear optical (NLO) properties were evaluated using the Z-scan technique with a continuous-wave Nd:YAG laser (532 nm wavelength). Results indicated that Ni incorporation significantly enhances both the nonlinear absorption coefficient and refractive index, making Ni@Bi2O3 nanorods promising candidates for nonlinear optical device applications.