Nowadays, the interest in microalgae for the recovery of bioactive molecules (polyphenols, and pigments) results in the production of by-products. This can be valorized through solid-state fermentation (SSF) for bioactive molecules recovery. Thus, the objective of the study was developed a solid-state biorefinery using S. platensis by-products (SPBP) as a substrate to recover bioactive fractions using A. oryzae. The study englobed chemical evaluation (composition, pH and radial growth); and fermentation (120 h) with protein (Bradford and amino acid quantification), organic acid and reducing sugar quantification; antioxidant activity; and the FPLC-profile. The results showed a higher content of protein and carbohydrates (35.09 ± 3.25 and 22.01 g/100g). The recovered extracts showed an increment in protein, reducing sugar (0.96 gEBSA/100g and 0.5 gE Glucose E/100g), amino acid contents and antioxidant activity: also, it was detected organic acids (malic and kojic acid). Finally, the protein fraction with lower molecular weight (1-3 kDa) could be involved in the antioxidant activity. The SSF biorefinery process allowed the recovery of extracts with increased antioxidant activity and valued-added molecules. Thus, the study sets a precedent for the integration of new bioprocessing technologies in the sea- industry for the recovery of value-added molecules.