This document defines the initial full specification for the PREDICT-6G system, building on the work that has been ongoing to produce intermediate versions on architecture matters in D1.1, D2.1 and D3.1. The PREDICT-6G architecture is presented starting with the design principles and the requirements on functional, non-functional and security levels. Based on the requirements, the architecture is described in a top-down approach, approaching from the end-to-end view, followed by separate Multi-domain Data Plane (MDP) and AI-driven Control Plane (AICP) views. The end-to-end deterministic service architecture model of PREDICT-6G is also discussed. The document provides a full reference of all architectural elements, including MDP components, AICP Management Domains, Management Services, APIs associated to the Management Services, and system and service procedures that define the interaction between the architectural components. The document also provides a methodology for implementing the PREDICT-6G system on top of different network technology domains, focusing on 3GPP and IETF DetNet as primary technologies.