Yttrium oxide (Y2O3) is a promising material for optoelectronic and high-frequency device applications due to its unique optical and electrical properties. In this study, we investigate the impact of Bismuth (Bi) and Zinc (Zn) doping, individually and in combination, on the structural, optical, and electrical properties of Y2O3. Doped Y₂O₃ samples were synthesized by simple precipitation methods, using Sodium Hydroxide (NaOH) and oxalic acid as precipitating agents, with 0.5 wt% of yttrium precursor as dopant concentrations. This work presents, for the first time, a comparative study that reveals how the combined effects of Bi and Zn co-doping together with the choice of precipitating agent control phase formation, lattice strain, and concurrent tuning of optical and electrical performance. X-ray diffraction (XRD) analysis confirmed that Bi doping facilitates phase formation, whereas Zn doping and co-doping suppress crystallization and increase lattice strain. UV–Vis absorption spectra showed a shift in absorption edge from ~ 250 nm (pure Y2O3) reaching the lowest absorption energy around 348 nm in the Bi-doped samples. Tauc plot analysis showed that the optical band gap (Eg) of Y2O3 varied from 5.23 eV (pure) to 3.85 eV (Bi-doped) depending on the synthesis route and dopant. The oxalic acid route produced slightly lower Eg values (by 0.1–0.3 eV) than the NaOH route, indicating enhanced defect formation and visible-light absorption. The trend Eg(Pure) > Eg(Zn-doped) > Eg(Bi-doped) ≈ Eg(Co-doped) confirms dopant-induced band tailing. Photoluminescence (PL) measurements demonstrated enhanced emission in Zn-doped Y2O3, while co-doping led to quenching due to dopant–dopant interactions. Impedance spectroscopy revealed that Bi–Zn co-doped Y2O3 exhibited the highest ionic conductivity, reaching 5.55 × 10⁻⁷ S·cm⁻1, particularly for NaOH-prepared samples. These findings demonstrate that co-doping strategy and precipitation chemistry strongly influence yttrium oxide’s structure–property relationships, making it a versatile candidate for luminescent and optoelectronic applications. © The Author(s), under exclusive licence to Springer Science+Business Media,