Dunaliella salina is well known for its ability to accumulate large amounts of β‐carotene. Myo‐inositol (MI) enhances the biomass production of D. salina, but the underlying mechanisms were unclear. The present study showed that the concentration of exogenous MI decreased gradually and reached a constant level at the 4th day of cultivation. MI enhanced the contents of total colored carotenoids and the activity of photosystem II. Metabolic profiles were significantly changed after the addition of exogenous MI, as revealed by multivariate statistical analysis. The metabolites could be categorized into four groups based on the relative levels in different samples. Exogenous MI increased the levels of most detected sugars, amino acids, and total saturated and unsaturated fatty acids. Based on the physiological and metabolic analyses, a hypothetical growth‐promoting model that MI promotes the growth of D. salina TG by increasing the levels of key metabolites and possibly enhancing photosynthesis, was proposed. This study provides valuable information for understanding the growth‐promoting mechanisms of MI in D. salina from the metabolic perspective.