Date seeds are byproducts of date processing and lack value beyond livestock feed. Our work focused on utilizing seed flours (defatted flour, F1, and ethanol-extracted defatted flour, F2) and testing their incorporation into cookies at different wheat flour substitution (10% and 30%). Flours and cookies were analyzed for their proximal and phenolic compositions, and antioxidant activity. Baking behavior, appearance and sensory studies were performed for cookies. Seed flours could be considered as food ingredients for their fiber content (84%), antioxidant properties (631–770 mmol TE/kg), and energy value (22–25 Kcal/100g). F1-Cookies had a higher texture (27–30 N) and phenolic content (0.5–1 g/kg) and a darker color. These characteristics made them less acceptable to the panelists, although their antioxidant activity was high (48–78 mmTE/kg). F2-Cookies were similar in texture (18–19 N) to the control, their color was intermediate between the control and F1, their phenolic content was about half of F1 (0.26–0.49 g/kg), and their antioxidant activity was higher than control (31–50 mmTE/kg). In three out of five parameters evaluated by the panel (odor, taste and texture), there were no significant differences between control and F2-10%. F2 flour would be an interesting product for baked good formulation, as F2-cookies had high fiber content, antioxidant activity, and good consumer acceptability. F1, but only at its lowest dosage (10%), could also be considered a valuable ingredient. This study demonstrated the potential use of date seeds for human consumption, producing healthy and nutritious foods that could promote economic and social development in date producing regions.