Chlorella spp., Spirulina spp., and fucoidan dry powders, are commercialized as food supplements and are considered safe for human consumption. Their broad-spectrum antiviral properties have been studied, however, their effect against SARS-CoV-2 remains unknown. We investigated the potential antiviral activity of three algae powders: Chlorella vulgaris, Spirulina máxima and fucoidan purified from marine brown algae Sargassum spp. against SARS-CoV-2 infection in vitro. Vero cells were incubated with 70 μg/ml of each algae powder and either 50 or 100 TCID50/ml of SARS-CoV-2. Chlorella powder inhibited SARS-CoV-2 infection; viral RNA was signifcantly reduced in supernatants at 24, 48, 72, and 96 hrs post-infection, the highest difference in viral load (8000-fold) was observed after 96 hrs. Spirulina maxima powder partially inhibited SARS-CoV-2 infection since no cytopathic effect was observed in 87.5% of infected cultures and viral RNA decreased 48 hrs after infection, reaching a 250-fold difference at 72hrs. In conclusion, our preliminary in vitro assays suggest that C. vulgaris and S. máxima dry algae, may potentially be used to fight COVID-19.