This research examines the effectiveness of dehydrated orange (Citrus sinensis L.) peel as a natural antioxidant agent to improve the quality and deterioration of used cooking oil. Orange peel powder was produced from fresh peels obtained from a traditional market in Cairo City, thereafter dried and processed to a consistent particle size. Different amounts of orange peel powder (5, 10, 15, and 20 g/100 mL oil) were incorporated into waste cooking oil, and the chemical and physical properties were assessed. The findings revealed that the control oil had a low content of free fatty acids and peroxides. Still, the used cooking oil (UCO) showed markedly elevated values, indicative of oxidative deterioration. Treatments (T) using dehydrated orange peel had differing impacts on AV and PV, with T1 (5 g/100 mL) displaying the highest values, indicating a pro-oxidant effect at this dose. Nonetheless, elevated amounts (T2, T3, and T4) significantly decreased oxidation indicators, improving the nutritional profile via an increase in advantageous fatty acids such as α-linolenic acid. The photometric colour index (PCI) indicated that reduced amounts markedly darkened the oil, whilst elevated concentrations preserved a hue more like that of the utilised oil. The viscosity measurements indicated that treatments with higher concentrations yielded reduced viscosities, possibly enhancing oil efficacy during frying. According to the findings, dried orange peel may improve the quality and performance of used cooking oil as a natural antioxidant, thus supporting sustainability in the food industry.