This study investigated the fatty acid (FA) compositions and proteins’ molecular weight profiles (MWP) of eight macroalgae species collected from the Antalya and Çanakkale in Turkiye: three red (Liagora viscida, Laurencia obtusa, Palisada perforata), three brown (Stypopodium schimperi, Cladostephus spongiosus, Halopteris scoparia), and two green (Caulerpa scalpelliformis, Penicillus capitatus). The potential bioactivities of the FAs were evaluated by in silico studies, focusing on anti‐cholinesterase, antioxidant, and cardioprotective effects. The predominant FA across all species was palmitic acid comprising over 50% of total FAs in most species. Docosahexaenoic acid (DHA) was abundant in seven of the eight species. Significant variations in MWPs were observed among species, with values ranging from <2532 to >67 000 Da. Brown algae generally exhibited higher MWP levels compared to red and green algae which showed distinctive profiles. In silico studies revealed that DHA exhibited the strongest binding affinity toward lipoxygenase acetylcholinesterase and butyrylcholinesterase enzymes with −8.829, −10.636, and −7.984 kcal mol−1 docking scores, respectively. DHA demonstrated significant interactions with key residues, forming hydrogen bonds critical for enzymatic inhibition and potential therapeutic effects. Molecular dynamics simulations confirmed the stability of DHA–protein complexes with low root mean square deviation and root mean square fluctuation values. This comprehensive analysis underscores the nutritional richness and potential bioactivity of macroalgae, particularly in terms of FA composition and protein profiles. The findings suggest that macroalgae, rich in DHA and other beneficial FAs, hold promise for pharmaceutical and nutraceutical applications, warranting further exploration into their therapeutic potential.Practical Applications: This study explores the fatty acid compositions and protein MWPs of eight macroalgae from Turkey's coasts. The findings suggest potential applications in aquaculture feeds and functional foods. Notably, DHA stands out for its antioxidant, cardioprotective, and cholinesterase inhibitor properties, making these macroalgae promising sources for obtaining DHA. The research supports practical applications in developing nutritional supplements, pharmaceuticals, and aquaculture practices, harnessing the bioactive potential of these marine resources for human health and industry.