In Drosophila, sexual differentiation, physiology, and behavior are thought to be mediated by numerous male- and female-specific effector genes whose expression is controlled by sex-specifically expressed transcriptional regulators. One such downstream effector gene, sex-specific enzyme 1 (sxe1, cyp4d21), has been identified in a screen for genes with sex-biased expression in the head. Sxe1 was also identified in another screen as a circadian regulated gene. Here, we analyzed the spatial and temporal regulation of sxe1 and identified a function for this gene in male courtship. We show that male-specific transcriptional regulator DSX(M) and the clock genes are necessary for cycling of sxe1 mRNA during the diurnal cycle. Similar to sxe1 mRNA, expression of SXE1 protein oscillates in a diurnal fashion, with highest protein levels occurring around midnight. SXE1 protein expression is restricted to nonneuronal cells associated with diverse sensory bristles of both the chemo- and mechanosensory systems. Suppression or knockout of sxe1 significantly reduces mating success throughout the diurnal cycle. Finally, the metabolomic profile of wild-type and sxe1 mutant males revealed that sxe1 likely functions as a fatty acid omega-hydroxylase, suggesting that male courtship and mating success is mediated by small compounds generated by this enzyme.