Abstract Symbiodiniaceae synthesizes bioactive substances like mycosporine-like amino acids (MAAs). To date, there has been little knowledge about the effects of light qualities on the growth and bioactive substance synthesis capacity of Symbiodiniaceae . In this study, we explored how four light qualities (i.e., white light (WL), red light (RL), blue light (BL), green light (GL)) affect the accumulation of biomass, biomacromolecules (i.e., polysaccharides, water-soluble proteins, lipids), and porphyra-334 (an MAA) in Effrenium voratum , a model species under the Symbiodiniaceae family. Our results indicate that BL promotes cell proliferation and porphyra-334 synthesis in E. voratum with higher energy conversion efficiency than WL, RL and GL do. In the end of the 24-day cultivation, the cell density of the BL group reached 6.19 × 10 5 cells·mL − 1 , 38%, 46%, and 183% higher than those of the WL, RL, and GL groups, respectively; the porphyra-334 concentration of the BL group reached 6.40 ± 0.26 nmol·L − 1 , 47%, 29%, and 147% higher than those of the WL, RL, and GL groups, respectively. The stronger promoting effect of BL is attributable to the higher light energy harvesting and electron turnover capacity of PS II and higher respiratory capacity of E. voratum under BL. Beyond that, this study revealed that BL performs better in promoting E. voratum to synthesize polysaccharides and water-soluble proteins. Overall, this study demonsrates that BL can serve as an inducer of cell proliferation and porphyra-334 synthesis in E. voratum , making itself a preferred light quality for the artificial cultivation of the microalga.