This study investigated the effect of gluten hydrolysates as a plasticizer in soy protein–wheat gluten (SP-WG) extrudates during high-moisture extrusion. The hydrolysis of WG increased its solubility and released small molecular peptides. In the case of SP-WG blends, the rheology results showed that the elasticity of WG decreased with the increase in the degree of hydrolysis (DH), which resulted in lower elasticity of SP-WG blends. Adding WG hydrolyzed for 1 h enhanced a fibrous appearance and the mechanical anisotropy of SP-WG extrudates. Confocal laser scanning microscopy images and bulk density showed that extrudates with WG hydrolysate had a looser structure, which is beneficial for the permeability and marinade release of extrudates. It can be concluded WG hydrolysate could be potentially used as a plasticizer in SP-WG extrudates and its plasticizing effect was governed by DH used.