<p><i>Nannochloropsis gaditana</i> is a marine microalgae popularly used as live feed in mariculture practices, but has potential human health benefits. In this study, the potential of <i>N. gaditana</i> to enrich the nutritional and antioxidant characteristics of cookies was evaluated. The algal biomass showed no cytotoxic activities in the cell lines tested, indicating its safety in food applications. The freeze-dried algal biomass was rich in protein (46.78%), fat (8.46%) and minerals (ash content 5.99%) and showed good levels of phytochemicals contributing to antioxidant activities. The freeze-dried <i>N. gaditana</i> was incorporated into cookies at 1, 1.5 and 2% replacement of refined wheat flour. Addition of <i>N. gaditana</i> in cookies significantly (<i>p</i> &lt; 0.05) increased the levels of protein, essential amino acid, total PUFAs and minerals, including sodium, calcium, potassium, iron, zinc and copper. In-vitro antioxidant activities of the cookies increased in parallel with the amount of algae added. The cookies with 1% and 1.5% algae had comparable/higher overall acceptability scores and showed comparable in-vitro protein digestibility to control cookies. The results of the study suggest that <i>N. gaditana</i> has potential application to enhance the nutritional and antioxidant properties of low-nutrition snacks such as cookies.</p> Graphical abstract <p></p>