We attempted to contribute to the stable income of citrus farmers by developing mayonnaise containing premature mandarin from Jeju. We confirmed the quality by comparing juice containing different premature mandarin content (0%, 25%, 50%, 75%, and 100%) with commercial mayonnaise. The color of premature mandarin mayonnaise was confirmed to have lower L* and a* values and higher b* values compared to commercial mayonnaise, thereby creating an image of a darker mayonnaise (P<0.05). Emulsion stability increased as the premature mandarin juice content increased, thus displaying excellent distribution and storage characteristics. Mayonnaise prepared with the addition of 100% premature mandarin juice was observed to have hardness, adhesiveness, cohesiveness, and springiness similar to commercial mayonnaise. Also, the chewiness of mayonnaise prepared with the addition of 50% premature mandarin juice was found to be similar to that of commercial mayonnaise (P<0.05). The functional superiority of premature mandarin mayonnaise was confirmed as the 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid assays showed a higher radical scavenging activity which increased in proportion to the increase in premature mandarin juice content (P<0.05). The acid and peroxide values of premature mandarin mayonnaise decreased in proportion to its premature mandarin juice content, ensuring better preservation of mayonnaise (P<0.05). Therefore, increases in the amount of premature mandarin juice resulted in superior functionality. Thus, it was confirmed that this product has a competitive advantage compared to commercial mayonnaise in addition to satisfying the consumers’ desire for health.