Otak-otak are processed products derived from surimi. Surimi is a myofibrillar protein concentrate of fish origin. Extended frozen storage can induce protein denaturation, consequently affecting end-product quality. During frozen storage, κ-carrageenan is a stabilizer, maintaining protein stability. This study aimed to evaluate the effects of kappa carrageenan addition to mackerel surimi on its quality during frozen storage and the resultant characteristics of the otak-otak as the end product. This study utilized a two-factor Completely Randomized Design (CRD), examining κ-carrageenan concentrations (0%, 1%, 1.5%, 2%) and cryogenic storage durations (7, 14, 21, 28 days). Analyses focused on surimi's rheological properties (gel strength, water holding capacity) and otak-otak's characteristics (protein, moisture, lipid content, and sensory attributes). Results indicated that 2% κ-carrageenan optimally preserved surimi quality during frozen storage, yielding the highest gel strength (2146-600 g/cm) and water holding capacity (71.44-55.16%). Otak-otak produced from surimi with 2% κ-carrageenan addition demonstrated superior characteristics, with optimal protein content (9.97-9.15%), moisture content (56.59-59.53%), and lipid content (0.66-0.69%). The organoleptic evaluation revealed the highest acceptability for otak-otak with a 2% k-carrageenan addition. Findings indicate that 2% κ-carrageenan optimally preserves surimi's physicochemical and organoleptic properties during 28-day storage, enhancing the frozen quality and yielding dense, chewy otak-otak products.