Large quantities of seashells and squid bones are discarded globally as biowaste, leading to serious environmental concerns. This work explores the conversion of these wastes into nano-hydroxyapatite (nHAp) using a simple and sustainable precipitation technique. The aim of the study was to establish an economical synthesis route while assessing the material’s suitability for biomedical applications. Hydroxyapatite is valued for its osteoconductivity-the ability to guide new bone formation and bioactivity-and its capacity to bond with living tissues, making it a promising candidate for bone regeneration. Comprehensive material characterization was carried out through FT-IR, XRD, SEM, TEM and EDAX. The analyses confirmed the development of phase-pure nHAp with uniform hexagonal and rod-like morphologies and high elemental purity. Antibacterial studies demonstrated significant inhibition zones against Listeria and Salmonella, with greater activity observed against Salmonella. The findings demonstrate that dual marine waste sources can be transformed into functional nHAp suitable for biomedical use. Beyond addressing waste management challenges, the study establishes a pathway toward scalable, low-cost biomaterials with potential applications in bone tissue engineering, implants, and regenerative medicine. © 2025 Elsevier B.V., All rights reserved.