This work aimed to use thermoplastic extrusion technology as a pretreatment for whole grain flours (corn, parboiled brown rice, and sorghum) and the incorporation of germinated millet at 5% for the production of gluten-free bread. The study characterized the flour (chemical composition and particle size distribution), evaluated the dough (pasting, empirical and fundamental rheological properties) and analyzed the bread quality characteristics (physical, structural, and textural measurements). Thermoplastic extrusion enabled the development of consistency, improved water absorption (105–153%) and viscoelastic properties of the doughs. This process caused an increase of the specific volume (66, 33 and 82%, respectively for corn, rice and sorghum made bread), and formation of better internal air cell distribution in the three different breads produced, especially in the sorghum bread. In addition, parboiled brown rice showed atypical pasting and rheological properties of the dough, which also affected the quality characteristics of the bread. The incorporation of 5% germinated millet enhanced breadcrumb softness in all samples, particularly for extruded rice flour added of germinated millet flour sample, which presented similar hardness values (7.3 N) and springiness (0.97) to whole wheat flour.