Induction welding of thermoplastic composites offers significant benefits in the aeronautical industry, such as weight reduction and enabling the joining of advanced materials like Carbon Fibre Reinforced Polymers (CFRP). However, its implementation faces various challenges due to the complexity of the process, which involves multiple interdependent parameters. Multiscale models address these challenges by simulating the behavior of the joint at different levels, from macroscopic to microstructural. This approach allows for process optimization, quality prediction, and ensuring adequate mechanical properties of the welded joints. This study focuses on applying multiscale models to predict the behaviour of induction-welded joints in CFRP. The developed model integrates different levels of analysis to replicate the structural state of the joint, considering critical parameters such as the degree of crystallisation of the thermoplastic polymer, which directly influences the joint's strength and durability, and the thermal map generated during the welding process. First, a high fidelity model simulates the welding process, creating a virtual representation of it. The data gathered is used to construct a microstructural model that provides insights into the joint's behavior based on key physical-chemical parameters present during the joining process. This information is then incorporated into a macroscopic model that reproduces the behavior of the welded joint during Lap Shear testing.The model evaluates the shear strength of bonded joints, establishing correlations with variations in process parameters, thereby enabling the prediction of the mechanical properties of the welded joint for a specified set of conditions. The model is validated through a series of experimental tests that assess its predictive capability. Data from these tests are compared with the simulation results. Through this methodology, the proposed approach is aimed to predict the behavior of the joints and identify critical areas for optimizing the induction welding process of CFRP materials.