<p>Gluten is the primary protein in wheat; however, its poor functional properties limit its application in the food industry. This study investigated the effects of ultrasound power (0, 300, and 600 W) on the functional properties of gluten subjected to extreme pH-shifting, and elucidated the underlying mechanism through analyses of molecular weight, free sulfhydryl content, surface hydrophobicity, secondary structure, and microstructure. The results demonstrated that 600 W ultrasound combined with pH 13.0 shifting significantly increased solubility from 1.60% to 15.69%, improved foaming capacity from 23.87% to 74.03%, and enhanced the emulsifying activity index from 3.05 to 34.85 m²/g. Meanwhile, a 300 W ultrasound combined with pH 11.0 shifting improved foam stability from 27.22% to 63.03%. However, ultrasound combined with pH-shifting treatment reduced the emulsion stability of modified gluten, irrespective of ultrasound power or acidic/alkaline conditions. Under acidic pH-shifting conditions, ultrasound increased the free sulfhydryl content (with the maximum change observed from 2.59 to 5.72&#xa0;µmol/g at pH 2.0); conversely, it decreased the free sulfhydryl content under alkaline pH-shifting conditions (from 6.52 to 1.77&#xa0;µmol/g at pH 13.0). Furthermore, 600 W ultrasound combined with pH 13.0 shifting elevated the surface hydrophobicity of gluten from 72.96 to 1357, increased the β-sheet content from 42.13% to 56.36%, and reduced the β-turn structure from 31.12% to 17.14%. Microstructural analysis revealed that ultrasound reduced the particle size of pH-shifted gluten, leading to fragmented structures. These findings may broaden the potential applications of gluten in the food industry and provide a theoretical foundation for the modification and valorization of other water-insoluble proteins.</p> Graphical Abstract <p></p>