Nowadays, there is a strong trend towards the use of functionally graded materials, with particular importance for the functionally graded joints. The main objective of this work was to study a functionally modified adhesive in order to have mechanical properties that vary gradually along the overlap of a joint, allowing a uniform stress distribution along the overlap. This allows for a stronger and more efficient adhesive joint and would permit to work with much smaller areas, reducing considerably the weight of the structure which is a key factor in the transport industry. In the proposed joint, the adhesive stiffness varies along the overlap, being maximum in the middle and minimum at the ends of the overlap. The functionally graded joint was found to have a higher joint strength compared to the cases where the adhesive has homogeneous properties along the overlap. A simple analytical model to study the performance of the functionally graded joints was developed. The differential equation of this model was solved by a power series. Numerical modelling by finite element analysis was performed to validate the analytical model developed.