Critical cybersecurity challenges associated with Mechatronic systems, the Internet of Things (IoT), the Industrial Internet of Things (IIoT), and Operational Technology (OT) are examined. The vulnerabilities in interconnected systems, as demonstrated by attacks such as Stuxnet, are shown to have potentially severe consequences. The expansion of IoT has been identified as a factor that significantly increases the attack surface, thereby raising both the likelihood and impact of cyberattacks. A cybersecurity lifecycle model is proposed, which emphasises continuous improvement through iterative phases of system building, attacking, and investigating. Secure software engineering practices, threat modelling for IoT, the integration of blockchain technology, and forensic techniques for IoT devices are discussed as potential solutions. The paper concludes that the inherent vulnerabilities in these systems necessitate a proactive focus on secure design and collaboration across disciplines to reduce cyber risks.