Introduction: The increasingly widespread resistance of malaria parasites to currently available anti-malarial drugs has encouraged researchers to search for natural ingredients that are safe and effective in eradicating malaria. Previously, the search for natural medicinal ingredients was performed by exploiting organisms on land. This trend has changed, and marine-derived medicinal ingredients have become increasingly in demand. This study was conducted to investigate the potential of red seaweed (Eucheuma cottonii) and brown seaweed (Sargassum polycystum) as antiplasmodial agents against Plasmodium falciparum. Methodology: Ethanol extracts of the two seaweeds were qualitatively tested for the presence of saponins, alkaloids, flavonoids, tannins, and terpenoids. Gas chromatography–mass spectrometry was performed to determine the metabolite profiles of the extracts. The antiplasmodial properties of the extracts against malaria parasites were determined by calculating the percentage of parasitemia inhibition, which was then used as a variable in probit analysis to determine the IC50 values of the extracts. Results: Saponins, alkaloids, flavonoids, tannins, and terpenoids were identified in the extracts. Hexadecanoic acid (CAS) palmitic acid, and heptadecene-(8)-carbonic acid-(1) were found in both extracts, where asazulene (CAS) cyclopentacycloheptene,1,2-benzenedicarboxylic acid, and dioctyl ester (CAS) dioctyl phthalate were identified only in the brown seaweed extract. Probit analysis in the anti-plasmodial assays revealed that the IC50 values of the red and brown seaweed extracts were 11.067and 10.214µg/mL, respectively. Conclusions: Given their IC50 values, the red and brown seaweed extracts can be categorized as active anti-plasmodials. Thus, they could be developed as anti-malarial ingredients.