Terminalia catappa (tropical almond) represents an underutilized resource with potential applications in functional food development. This study investigated the technological properties and bioactive characteristics of T. catappa kernel flour and its application in cookie formulation. The research examined the techno-functional properties, pasting behavior, and bioactive profile of T. catappa flour and its blends with different sweeteners (erythritol and cane sugar at 5% and 15% concentrations). Cookies were formulated using optimized ingredients, and their quality parameters were evaluated through physical, chemical, and sensory analyses. T. catappa flour demonstrated significant water holding capacity (4.48 g H2O/g DM) and notable antioxidant activity in both aqueous and ethanolic extracts (DPPH: 1.95–3.35 mg TE/g DM). The addition of sweeteners influenced pasting properties, with higher concentrations generally reducing peak viscosity and pasting temperature. Developed cookies exhibited stable water activity (0.294–0.320) over one month of storage and contained substantial dietary fiber (5.018 g/100 g). Sensory evaluation revealed superior acceptability for thicker (10 mm) cookies, particularly in texture and appearance attributes. This study establishes T. catappa kernel flour as a promising functional ingredient for gluten-free bakery applications, offering both technological functionality and bioactive properties suitable for health-conscious product development.