Exogenous application of proline and silicon could improve drought tolerance mechanisms in cowpea. In this study, we assessed the exogenous application of proline and silicon to reduce drought stress in cowpea. For this, we evaluated physiological, biochemical, and growth indicators of “BRS Guariba” cowpea in two phenological stages. The experiment was installed in a completely randomized design with five treatments, comprising a control treatment and four drought stress treatments—with and without application of proline and silicon in the V5 and V9 phenological stages. Cowpea plants subjected to drought stress—in both V5 and V9 stages—showed increases in proline concentration and activity of antioxidant enzymes, but this behavior failed to mitigate water restriction on growth indicators. However, the exogenous application of proline and silicon, mainly separately, restored leaf water potential, and the increased proline concentration and antioxidant enzymatic activity mitigated drought stress on cowpea growth. Exogenous application of proline plus silicon mitigates drought stress on cowpea in two phenological stages.