The purpose of this study was to determine how adding rosemary oil influenced the chemical, microbiological, and sensory properties of cakes. Three samples were prepared: one with pure oil (-), one with oil plus BHT (+), and one with rosemary oil (R). A sample of rosemary oil is used as an antioxidant and antifungal to improve the shelf life of the cake. The extracted oil was tested for DPPH and Well Diffusion, as well as sensory tests (taste, smell, texture, color, porosity, general acceptance), chemical composition (moisture, ash, protein, fat, carbs), and oil quality (peroxide value, acid value). Moisture levels were checked regularly, and obvious fungal growths on the finished product (cake) were counted weekly.We discovered that rosemary oil can be utilized as a natural antioxidant and antifungal instead of artificial preservatives to improve shelf life with comparable results. The findings revealed that rosemary oil has antioxidant activity in the cake product, as the peroxide number of the oil extracted from the cake did not exceed 10 ml equivalent/kg by the fourth week of manufacture, and the acid value did not exceed 0.6 mg/g for two weeks. The DPPH test for rosemary oil yielded an IC50 of 44 mg/mL.The findings also showed that rosemary oil had antifungal properties, as fungal growths were visible and began to develop after three weeks on the cake from the date of manufacturing .In conclusion, rosemary oil can be utilized as a safe natural antioxidant to prevent oxidation and extend the shelf life of cake.