The chemical and volatile composition as well as sensory profile of five brown edible seaweeds collected in the United Kingdom, was evaluated. The ash content was 190–280 mg/g, NaCl 35.1–115.1 mg/g, protein 2.9–6.0 g/g, and fat 0.6–5.8 g/g (dry basis). Fucus vesiculosus, Fucus spiralis and Ascophyllum nodosum showed higher antioxidant activities (DPPH and FRAP). Nucleotide concentrations were of the same order of magnitude as reported in other foods such as tomatoes or potatoes, except for F. vesiculosus where levels of nucleotides were 10 times higher. The fatty acids profile was dominated by oleic acid (21.9–41.45%), followed by myristic (6.63–26.75%) and palmitic (9.23–16.91%). Glutamic and aspartic acids (0.15–1.8 mg/g and 0.05–3.1 mg/g) were the most abundant amino acids. Finally, sensory and volatile analyses illustrated that Laminaria sp. had the strongest seaweed and seafood-like aroma and taste.