<p>Pure and Magnesium (1 and 3 mol%) doped <i>β</i>-Ga₂O₃ nanostructures were synthesized by hydrothermal method followed by calcination at 1000°C. The monoclinic structure of stable <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\upbeta }\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">β</mi> </math></EquationSource> </InlineEquation>-phase was confirmed by X-Ray Diffraction. Peak shifting towards lower 2<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\uptheta }\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">θ</mi> </math></EquationSource> </InlineEquation> values has been observed from XRD data due to Mg doping. FESEM analysis revealed the transformation of cocoon-like shape into a spindle structure upon increase of Mg concentration. The elemental composition was obtained from EDAX. Phase purity of synthesized materials was confirmed by FTIR results. Also, various vibrational bands were identified from the FTIR plot. Optical properties were studied using UV-Visible Spectroscope and Photoluminescence Spectroscope. Photocatalytic performance towards Rhodamine B dye was&#xa0;studied under UV irradiation for various time durations. All Mg-doped samples exhibited enhanced photocatalytic activity than that of pure <i>β</i>-Ga₂O₃. Specifically, 3 mol% Mg-doped <i>β</i>-Ga₂O₃ showed the highest degradation efficiency of 92% in a time interval of 150 minutes. The enhanced performance has been justified by the recorded characterization results. The reaction kinetics and dye degradation mechanism has also been proposed for clear understanding of Rhodamine B degradation.</p>