Astaxanthin is a popular carotenoid widely noted for its excellent antioxidant and numerous biological activities. At present, it is of high demand for human consumption in the nutraceutical and food industries. Xanthophyllomyces dendrorhous is one of the most promising sources of natural astaxanthin. Its industrial adoption is however stunted by low productivity. One of the solutions being explored is addition of exogenous substances to cultures to stimulate astaxanthin production. The present study investigates the effect of 2,4-Dichlorophenoxyacetic acid (2,4-D), synthetic auxin, on the growth and astaxanthin synthesis of X. dendrorhous. The results revealed that all tested concentrations (5–50 mg/L) did not have a significant impact on biomass accumulation as well as overall sugar consumption by the yeast. In contrast, 5–30 mg/L of 2,4-D significantly increase astaxanthin production by the yeast up to 1.5-fold compared to the control. 2,4-D treatment within this concentration range also significantly increased astaxanthin content of biomass.