Over the last decade there has been an influx in pelagic sargassum spp. (brown seaweed) in the Caribbean due to climate change. Seaweed is a good candidate for the fabrication of bioplastics because of its high biomass and its ability to grow in a wide range of environments. Herein, we propose a method to valorize sargassum spp. in St. Vincent and the Grenadines to produce bioplastics as an alternative to petrol-based plastics. The extraction of Na alginate and cellulose from the brown seaweed and the characterization of the polymers by FTIR spectroscopy, NMR spectroscopy and PXRD are outlined. Thin films were prepared using blends of the unprocessed seaweed, ands its extracted components: Na alginate, Ca alginate and cellulose, with locally produced arrowroot starch and glycerol in various ratios, via solvent casting. The mechanical strength and water vapor permeability (WVP) of the various films were then assessed.