This thesis explores the origins and rationale behind the requirement for a Fundamental Rights Impact Assessment (FRIA) within the AI Act, examining how the EU legislator has structured the assessment of fundamental rights impacts and identifying the methodological principles necessary for its effective implementation. Through a detailed legal analysis of the AI Act and a review of various assessment frameworks, the thesis provides a comprehensive perspective on these critical issues. The primary aim of this thesis is to address gaps in the theoretical and methodological development of the FRIA as envisioned in the AI Act. By designing a software tool that translates the FRIA methodology into a practical application, the project seeks to support EU and national authorities, as well as AI developers, in embedding this essential mechanism into the broader framework of human-centric and trustworthy AI.