Ulva seaweed is a viable raw material for the production of analog rice since it is plentiful in the coastal waters of Buton Island, Indonesia, and contains rich nutritional elements (dietary fiber, polysaccharides, minerals, and antioxidant metabolites). This study investigated and characterized ulvan from Ulva sp seaweed collected in Buton Island and evaluated its potential as a functional food ingredient through physicochemical characterization and proton nuclear magnetic resonance (H-NMR) metabolite profiling. Fresh Ulva samples were collected from the coastal area of Wagola and Hone Beaches (Buton Island), cleaned, dried, and processed into flour. For the bioactive compound examination, the extraction used a microwave method with several times (10, 15, 25 minutes). The seaweed was characterized for its physicochemical properties, and metabolites were extracted for ¹H-NMR analysis to identify major bioactive compounds. The results showed that the extraction duration affects yields, with 25 minutes yielding the maximum yield when compared to 10 and 15 minutes. Functional group analysis (FTIR) results verified that the polymer generated was a sulphated polysaccharide. Polysaccharides have a melting point between 224.9 and 228.9 ºC. The toxicity of polysaccharide extracts using the Brine Shrimp Lethality Test (BSLT) method indicates that these polysaccharides showed cytotoxic activity. The ability of Ulva Wagola Extract (UWE) and Ulva Hone Extract (UHE) to proliferate cells was proven by cell toxicity using NIH3T3. According to the ensuing anticancer data, UHE and Sargassum Wagola Extract (SWE) tend to prevent MBA-MB cancer cells from proliferating. Polysaccharide antioxidant values were moderate for UWE (87,62 mg/L), weak for UHE (172,45 mg/L), and extremely weak for SWE (251,08 mg/L); and the ulvan had a sulphate content of 8.7 w/w%. The compositional constitution encompassed β-d-glucuronic acid, α-l-iduronic acid, 1,4-linked α-l-rhamnose substituted with side-chain, 1,4-linked α-l-rhamnose, and β-d-xylose.  Overall, the characterization confirms that Ulva seaweed from Buton Island represents a promising renewable resource for analog rice raw materials and supports its future development as functional food.