Biomass derived supplements have been recognized as environment-friendly and cost-effective sources of stimulants which can promote growth and valuable metabolites biosynthesis of microalgae. In this research, effect of lignosulfonates (LIGNs) on the growth, cell morphological changes, and valuable products accumulation of microalga Euglena gracilis was explored. At the optimal concentration of 5000 mg·L−1, LIGNs could promote the growth of E. gracilis up to 1.95 folds, and increase the yield of chlorophyll a, chlorophyll b and carotenoids by 3.50, 1.59 and 3.48 times, respectively. Cell morphological changes in aspect ratio and size caused by LIGNs were also observed. Fourier transform infrared spectroscopy measurements followed by multivariate analysis revealed difference in metabolic patterns and prominent metabolites with LIGNs treatment. LIGNs improved the lipid yield since both cell density and lipid content increased, which could contribute to the biofuel production in the future.