TELEMETRY will provide trustworthy tools that enable the continuous assessment of heterogenous, interlinked components & systems that constitute IoT ecosystems (interconnected IoT devices with hardware, software, services and communications infrastructure). Addressing all aspects of their lifecycle, the TELEMETRY holistic methodology and toolkit incorporates: testing for component development, testing & monitoring for component integration into systems, testing & monitoring for operation of systems. TELEMETRY will deliver advances in cybersecurity testing and runtime monitoring through the use of novel machine learning models and algorithms for real-time anomaly detection; dynamic risk assessment to simulate likelihood and severity of threat consequences; reputation management and privacy-preserving data sharing across independent entities (e.g. supply chains), IoT device emulation and analysis environment and lightweight approaches for trusted updates; all of which that promotes a cycle of continuous improvement and assurance across design and runtime phases. TELEMETRY will leverage 3 exemplar use cases representing diverse, complex IoT ecosystems and IoT supply chains in aerospace, smart manufacturing and telecommunications domains to drive the design and validation of the proposed tools and methodologies. This will lead to significant improvements with respect to accuracy of threat and vulnerability detection, response time and cost of testing and verification of IoT ecosystems. TELEMETRY will promote open source and knowledge sharing through engagement with relevant communities throughout the project for consultation, dissemination and exploitation of its results.