<p>This paper reports the synthesis of bismuth iron oxide (BFO) nanostructures containing BiFeO₃, Bi₂₅FeO₄₀, and BiFe₂O₉ compounds by a simple sonochemical method. Also, the effect of different parameters including the source of hydroxide ion production, synthesis temperature, and calcination temperature on the composition, structure, and morphology of the products were investigated. XRD, EDS, EDS-mapping, FT-IR, FESEM, and DRS analyzes were used to check the composition, structure, morphology, and other characteristics of the synthesized products. According to the amorphous nature of the samples based on the XRD results, calcination was performed at 500&#xa0;°C for one hour. In order to produce products with better crystallinity and uniformity, the synthesis temperature was controlled using an ice bath. The DRS results demonstrated the high capability of the synthesized bismuth iron oxide compounds for light absorption, making them suitable for photocatalytic applications. According to the photocatalytic degradation results, the synthesized products exhibited a strong ability to degrade methylene blue. The Bi₂Fe₄O₉/BiFeO₃ and Bi₂₅Fe₄₀ compounds showed significant performance, with degradation efficiencies of 96.8% and 99.64%, respectively, under UVA light irradiation. This study introduces a straightforward method for developing innovative and highly effective modified bismuth iron oxide nanostructures for application in photocatalysis.</p>