Carbon fibre-reinforced composites have excellent mechanical properties that may decay due to the presence of defects. Therefore, it is mandatory to understand the material behaviour and analyse the defects based on their detection and characterization. This paper focuses on Sheet Moulding Compound composites and proposes an experimental defect replication methodology to control and analyse the material behaviour during mechanical testing. Preliminary studies show the importance of investigating the change in mechanical properties based on the geometry of defects formed during the manufacturing process, including voids, porosity and delaminations. In particular, following the proposed method, voids and linear discontinuities were reproduced through material intrusions, with steel spheres and aluminium sheets respectively. Since defect replication is a crucial step and rigorous quality control is essential to ensure uniform distribution of defects, the use of advanced techniques such as Computed Tomography is essential to ensure a correct set-up of the experimental tests confirming the actual geometry of the defect. The material was characterized through ASTM mechanical tests, therefore standardised specimens were produced. These experimental results highlight the correlation with the mechanical properties decay, contributing significantly to a deeper understanding of the application limits of the Sheet Moulding Compound composites. Therefore, the defects highlighted in the Computed Tomography images of real components can be analysed and classified, understanding whether they can be accepted or rejected for functional purposes based on their presence and size. This innovative approach can open up new study possibilities and provide further information on the material’s response to defect geometries.