The present study investigates the structural characterization and bioactivity of macroalgal polysaccharides (laminarin and fucoidan) extracted and purified from Chorda filum collected from Kongsfjorden, Arctic. The extraction was done using a hydrothermal-assisted extraction method followed by purification using ion exchange and size-exclusion chromatography. Two purified fractions, Chorda purified fraction (CPF) 1 (neutral) and CPF 2 (anionic), were obtained and examined for their bioactivity and chemical characterization. The major fraction CPF1 displayed notable free radical inhibition activities: 1, 1-diphenyl-2-picryl-hydrazyl (IC50 5.21 ± 0.24 mg mL-1), 2, 2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (IC50 3.28 ± 0.04 mg mL-1), and hydrogen peroxide (IC50 3.06 ± 0.12 mg mL-1). It also exhibited strong α-glucosidase enzyme inhibition activity (IC50 0.125 ± 0.012 mg mL-1), equivalent to the model commercial compound acarbose. Fourier-transform infrared (FTIR) analysis of CPF1 indicated O-H, C-H, CO, C-C, and C-O stretching, reflected by peaks at 3335 cm-1, 2919 cm-1, 1369 cm-1, 1100 cm-1, and 1030 cm-1, respectively. The monosaccharide composition CPF1 revealed a major composition of glucose with mannitol residues. The 1H Nuclear magnetic resonance (NMR) peaks at δ 3.3-3.6 ppm, δ 3.5-3.7 ppm, δ 3.6-3.9 ppm, δ 4.3-4.5 ppm, δ 4.6-4.8 ppm and δ 5.1-5.3 ppm and 13C NMR spectrum peak at δ60.66, 68.08, 73.28, 75.60, 84.11, and 102.5 ppm corresponded to C6, C4, C5, C2, C3, and C1 of m-type β-(1, 3)-glucan structure. The molecular mass of CPF1 using gel permeation chromatography (GPC) was found to be approximately 64 kDa. In summary, CPF1, a bioactive, m-type laminarin, was successfully extracted and purified from the understudied filamentous macroalgae C. filum.