Real-time path deviation detection is critical for sensitive applications such as military convoys, cash-in-transit services, and armored vehicle operations. Here, the safety of vehicles and personnel must be ensured throughout the journey. These systems are vulnerable to adversarial attacks, particularly on the communication framework that continuously monitors vehicle paths. These adversaries can compromise detection accuracy and endanger missions. To address this challenge, we propose a secure real-time Path Deviation Detection (PDD) system that leverages blockchain technology. Blockchain provides immutability, transparency, and decentralized trust, thereby safeguarding both data integrity and communication reliability. By integrating blockchain into the monitoring framework, the proposed system resists tampering, enhances operational reliability, and ensures accurate detection of deviations in real time. This approach not only strengthens the security of vehicular operations, but also establishes a foundation for the deployment of trusted path monitoring solutions in critical domains that require high assurance and resilience against cyber-physical threats.