This experiment aimed to analyze the antioxidant capacity and composition of polyphenolic compounds from date seed beverage produced from eight date palm cultivars subjected to three roasting temperatures (180°C, 200°C, and 220°C) from light roasting to dark roasting. Total phenolic content in date seed beverages at light roasting ranged from 4.98 to 14.09 mg GAE/g, higher than that of the medium roasting (3.66-8.65 mg GAE/g) and dark roasting intensity (1.66-6.33 mg GAE/g). Date seed beverages produced from lightly roasted seeds had higher antioxidant capacity than those roasted at medium and dark levels. Using LC-ESI-QTOF-MS/MS, a total of 69 polyphenolic compounds were detected, classified into three groups: 17 phenolic acids, 40 flavonoids, and 12 other phenolic compounds. Our findings demonstrated a decrease in phenolic content as date seed roasting intensity increased from light to dark roasting, accompanied by variations in both phenolic composition and antioxidant capacity across cultivars.