Background <p><i>Chlorella vulgaris</i> is a green microalga known for its high protein content, nutritional value, beneficial health effects, and natural antioxidants. The present research focused on the enzymatic breakdown of <i>Chlorella vulgaris</i> biomass utilizing pepsin and promod enzymes, as well as the assessment of the antioxidant properties of the resulting peptide fractions.</p> Methods <p>Bioactive peptides were extracted from <i>C. vulgaris</i> using enzymatic hydrolysis with proteases pepsin and Promod. The enzyme hydrolysates were ultrafiltered using Amicon membranes with molecular weight cutoffs of 10 kDa and 3 kDa. The antioxidant properties of chlorella protein hydrolysate were evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and reduction power assays at concentrations ranging from 0.375 to 6 mg/ml. The protein extraction levels from pepsin and promod were measured at 18.60 mg/ml and 3.26 mg/ml, respectively.</p> Results <p>The findings showed that the peptide fractions smaller than 3 kDa from both pepsin and promod demonstrated the most significant DPPH radical scavenging activities, with percentages of 12.49% ± 0.314% and 7.14% ± 0.091% at a concentration of 6 mg/ml, respectively. Similarly, these fractions demonstrated the highest reducing power, with absorbance values of 0.781% ± 0.054% and 0.196% ± 0.011% at a 6 mg/ml concentration, respectively.</p> Conclusions <p>This study extracted bioactive peptides from <i>Chlorella vulgaris</i> using commercial proteases, achieving a protein extraction efficiency of 3.80% and a protein content of 47.02%. Hydrolysis with pepsin and Promod enzymes produced proteins with DPPH free radical inhibition that increased with concentration, with pepsin showing greater activity. Both hydrolysates exhibited reducing power (FRAP), with pepsin outperforming Promod. These findings suggest that <i>Chlorella vulgaris</i> enzymatic hydrolysates could be potential antioxidants for functional foods.</p>