We present a fully discrete finite element method for the interior null controllability problem subject to the wave equation. For the numerical scheme, piecewise affine continuous elements in space and finite differences in time are considered. We show that if the sharp geometric control condition holds, our numerical scheme yields the optimal rate of convergence with respect to the space-time mesh parameter. The approach is based on the design of stabilization terms for the discrete scheme with the goal of minimizing the computational error.