The convergence of blockchain technology with metaverse platforms presents significant opportunities for innovation but also introduces critical challenges in ensuring security, privacy, and trust. This paper addresses these challenges by proposing a comprehensive security framework tailored for blockchain-based metaverse environments. Our approach integrates advanced cryptographic techniques, privacy-preserving protocols, and decentralized trust mechanisms to enhance the overall security and user trust in these platforms. We present a detailed analysis of our multi-layered security model, which includes secure identity management, encrypted data storage, and robust transaction verification processes. Through extensive simulations and real-world case studies, we demonstrate the effectiveness of our framework in mitigating common security threats and preserving user privacy. Our results show substantial improvements in security and privacy metrics compared to existing solutions, highlighting the potential of our approach to set new standards for trustworthy blockchain-based metaverse applications. We conclude by discussing the broader implications of our findings and outlining future research directions to further enhance security and trust in this rapidly evolving field.