Dislocation slip is a fundamental deformation mechanism in metallic materials. Full-field crystal plasticity (CP) modeling provides a framework for the constitutive description of this dislocation-mediated plasticity, using formulations such as phenomenological power-law relations. This can account for strengthening phenomena including precipitation hardening, solid-solution strengthening, and work hardening by explicitly quantifying their respective contributions to the critical resolved shear stress. In the context of thermo-mechanical processing, the coupling between plastic deformation and precipitate evolution is referred to as dynamic ageing. Here, the accumulation of plastic strain, along with the increase in dislocation density and excess vacancies, significantly influences the nucleation, growth, and dissolution kinetics of secondary phases. This study employs a coupled computational framework that combines a full-field crystal plasticity (CP) model, based on the multiphase-field (MPF) formalism, with a Kampmann–Wagner numerical (KWN) model to predict the strain-dependent evolution of η' (Mg5Zn7Al6) precipitates in an Al–Zn–Mg–Cu alloy. By defining grains through continuous order parameters, the MPF formulation explicitly resolves grain boundary migration and recrystallization while maintaining stable during large deformations. However, because precipitation phenomena occur at length scales significantly smaller than the mesoscopic grains resolved by full-field CP, explicit spatial resolution of the precipitates is computationally intractable. To bridge this separation of scales, a mean-field approach is adopted to derive the local precipitate size distribution and volume fraction from the thermo-mechanical history. These microstructural variables are dynamically linked to the CP constitutive laws, where they govern the evolution of the critical resolved shear stress. Ultimately, this framework demonstrates the coupling between dynamic ageing, recrystallization kinetics, and macroscopic mechanical behavior.