This study investigated the quality characteristics and antioxidant activities of gluten-free cookies containing teff flour. By substituting 0% (control), 25% (TF25), 50% (TF50), 75% (TF75), and 100% (TF100) of wheat flour with teff flour, five samples were produced. Baking loss rate was the highest in TF25 at 13.76% and the lowest in TF75 at 4.03%. Spread factor was significantly higher in cookies made with teff flour (83.00~85.00) than in the control (81.33) (p<0.05). There was no significant difference in density among the samples at 1.17~1.25 g/mL (p<0.05); however, pH significantly decreased at 6.42~6.04 (p<0.05). While the L-value and b-value significantly decreased with the amount of teff flour, the a-value significantly increased (p<0.05). The ΔE value was the highest in the control at 31.31 and the lowest in TF100 at 58.69. Hardness was the highest in the control at 42.04 N than in cookies containing teff flour. The content of polyphenols was the highest in TF100 at 3.37 μg GAE/mg and the lowest in the control at 1.32 μg GAE/mg. The content of flavonoids was the highest in TF100 at 3.66 μg QE/mg and the lowest in controls at 0.45 μg QE/mg. The value of DPPH IC50 was the highest in the control at 3,723.00 μg/mL and the lowest in TF 100 at 405.27 μg/mL. The value of ABTS IC50 was the highest in the control at 1,822.32 μg/mL and the lowest in TF100 at 529.30 μg/mL. In sensory evaluation, while control, TF75, and TF100 had a higher score in appearance at 5.52~5.60, all samples had no significant differences in flavor, sweetness, savory taste, chewiness, and overall acceptability (p<0.05). These results showed that the gluten-free cookies containing teff flour can improve the quality characteristics and antioxidant activities of a cookie. We concluded that gluten-free cookies containing 100% teff flour are desirable.