Purpose: In this study, we sought to determine the impact of transglutaminase (TG) reaction on the structural and functional properties of textured vegetable protein (TVP) and to explore optimal conditions for TG reaction that can improve quality characteristics. Methods: TVP was immersed, moisture was removed, homogenized, and used as an experimental material. After mixing with TG, it was reacted at 5℃, 15℃, 25℃, and 50℃ for 240 min, 100 min, 60 min, and 10 min, respectively. TVP-TG emulsion was prepared and pH, color, moisture content, emulsion stability, textural properties, and cooking loss were measured. Amino acid analysis and differential scanning calorimetry (DSC) were carried out. Results: When TVP was subjected to TG reaction, the pH tended to increase, and the lightness and yellowness of the emulsion after heating also appeared to increase. The amino acid content and moisture content were highest at 25℃. Emulsion stability was lower values for both the total (water and fat) separation amount and fat separation amount during the TG treatment compared to the control group. Thermal property measurements showed that both thermal denaturation temperature and denaturation capacity were highest at 25℃, but no significant difference was observed. Hardness was significantly higher when TG was reacted at 5℃ and 25℃. Conclusion: TG treatment affected the structural and functional properties of TVP. No significant difference was observed with varying TG content, and 25℃ could be considered the optimal condition for the reaction.