Macroalgae from the Moroccan Atlantic and Mediterranean coasts have been investigated as sources of bioactive preparations for biomedical, agricultural and environmental applications. This narrative review updates the 2016 overview of Moroccan seaweed bioactivities and examines experimental studies published from January 2016 through August 2026. The synthesis focuses on locally harvested macroalgae, the preparations tested and the biological models used. The literature covers antioxidant and antimicrobial screening, digestive-enzyme inhibition, toxicity and cancer-cell assays, antiviral polysaccharides, vascular responses, wound healing, cyanobacterial growth inhibition and crop protection. Studies from Nador lagoon broaden the evidence for green and red algae, while work on Fucus spiralis, Sargassum muticum and sulfated polysaccharides extends the range of experimental applications. Seasonal comparisons and studies of extraction and drying show why activity must be interpreted in relation to the harvested and processed material. Animal experiments provide proof of concept for selected preparations, although efficacy and safety in humans remain unestablished. Differences in extraction, assay conditions, controls and replication restrict comparisons across studies. Chemical profiling and molecular docking add useful information but do not, on their own, identify the constituents responsible for activity or validate their targets. Further progress depends on traceable collection, reproducible preparation, activity-guided characterization and safety testing appropriate to the intended application.