Secure and transparent voting mechanisms are critical for maintaining the integrity of democratic processes. Conventional voting methods and existing electronic voting systems often suffer from centralized control, limited transparency, high operational cost, and vulnerability to manipulation. To address these challenges, this paper proposes a blockchain-based online voting system that ensures decentralization, immutability, and verifiable election processes. The proposed system leverages blockchain technology to record each vote as an immutable transaction, preventing unauthorized modification and ensuring end-to-end transparency. To enhance system security, role-based access control (RBAC) is implemented to restrict operations based on predefined user roles, thereby preventing unauthorized administrative actions. Additionally, a vote receipt verification mechanism is introduced, allowing voters to independently verify the inclusion of their vote in the blockchain without compromising voter anonymity. To further strengthen election integrity, an AI-based fraud detection module analyzes voting behavior and system activity patterns to detect and mitigate suspicious activities such as multiple voting attempts, abnormal access behavior, and automated attacks. The integration of blockchain, artificial intelligence, and access control mechanisms significantly improves voter trust, election transparency, and system reliability. Experimental analysis indicates that the proposed system reduces fraud risks, enhances verification efficiency, and supports scalable online elections, making it suitable for modern digital voting environments.