The rapid expansion of the Internet of Things (IoT) has introduced critical vulnerabilities at the sensor layer, as conventional cybersecurity measures often fail to address data integrity at its source, creating significant risks in modern cyber-physical systems. This research addresses the urgent need for a verifiable method to ensure the trustworthiness of sensor data. The primary aim of this paper is to propose and validate a novel framework for the metrological assurance of IoT sensors, designed to mitigate cybersecurity risks by treating data manipulations as quantifiable measurement anomalies. The proposed framework integrates two foundational technologies: Digital Calibration Certificates (DCC) to establish a trusted metrological baseline and Distributed Ledger Technology (DLT) to ensure its immutable traceability. A mathematical model is developed to formalize attack vectors and introduce the Dynamic Trust Corridor (DTC) criterion for real-time verification. The core result is the development of the Metrological Trust Index (MTI), a continuous metric for data trustworthiness. Through numerical simulation of an industrial sensor, the framework demonstrated a 98.7% detection rate for bias injection attacks and a 94.1% rate for subtle drift manipulation attacks, significantly outperforming traditional methods. Theoretically, this work establishes a new paradigm for IoT security rooted in the principles of measurement science. Practically, the framework provides a concrete, auditable pathway for manufacturers and operators to comply with emerging regulatory standards such as the EU Cyber Resilience Act (CRA), enhancing the overall resilience of critical IoT ecosystems.