One of the oldest oilseed crops is sesame, which is mainly cultivated due to its valuable oleic/linolenic fatty acid ratio. The application of precise irrigation and fertilisation is crucial to ensure the continuity and productivity of sesame production, especially in arid and semi-arid regions. This study aimed to determine the effect of drip irrigation and nitrogen levels on sesame’s oil and fatty acid composition. For this purpose, four nitrogen doses (N0: 0 kg ha−1, N30: 30 kg ha−1, N60: 60 kg ha−1 and N90: 90 kg ha−1) and three different irrigation water levels (I50, I75 and I100, which correspond to 50, 75 and 100% evaporation levels from the evaporation of the Class A pan) were applied. The highest oleic acid content (43.06%) was obtained for the I75N90 treatment. In the case of linoleic fatty acid, the greatest value (43.66%) was for I50N0 treatment. The effects of irrigation and nitrogen doses on oleic acid and linoleic acid content were inverse of each other. An increase in applied irrigation water increased the linoleic acid content. However, it caused a decrease in oleic acid content. Increasing the nitrogen dose increased the oleic acid content and caused a decrease in linoleic acid content. Furthermore, this study showed that the I50N60 treatment (50% Epan and a rate of 60 kg N ha−1) is the most effective for achieving high grain and oil yields in sesame cultivation. The results obtained provide practical guidance for farmers in sesame cultivation.