The chapter delves into the complexities of regulating artificial intelligence (AI) systems classified as high-risk under the European Union’s Artificial Intelligence Act (AI Act). The authors explore the challenges of defining and categorising high-risk AI systems, highlighting the dynamic evolution of legislative proposals and amendments. The text provides an in-depth analysis of key provisions, such as Article 6, which outlines the criteria for high-risk classification, and Annex III, detailing specific use cases and risk scenarios. The chapter emphasises the importance of implementing robust risk management systems, as required by Article 9 of the AI Act, and ensuring compliance with evolving cybersecurity, transparency, and accountability standards. It also examines the interplay between existing EU regulations, such as GDPR and NIS, and the requirements introduced by the AI Act. By addressing the responsibilities of AI providers, stakeholders, and regulators, the authors underline the need for a balanced and flexible regulatory framework. This work serves as a critical resource for understanding the intricacies of high-risk AI regulation, offering valuable insights for legislators, AI developers, and industry professionals.