The presence of a delamination in a bi-dimensional structure causes a discontinuity in the smoothness of the mode shapes on the perimeter of the damaged area. On this basis, in this paper, a numerical method proposed by the authors for detecting discontinuities in the first derivative of a smooth piecewise function, based on a Gaussian process regression (GPR) approach, has been applied to the problem of delamination localisation in multilayered composite plates. Using the finite-element method, the mode shapes of a multilayered composite plate with a delamination are calculated and used as input data for the damage localisation procedure. The performance of the approach are analysed for different sizes and through-the-thickness positions of the damage. Furthermore the problem of ‘boundary disturbance’, the erroneous indication that a fault is present near the edge of the plate exhibited when applying the GPR approach to bi-dimensional structures, is addressed using an extrapolation procedure. The effect of noise is also investigated in order to demonstrate the effectiveness and the versatility of the method in localising delaminations.