<p>This paper introduces piecewise discrete Krawtchouk functions (PDKFs) as a novel approach for solving fractional optimal control and variational problems involving the piecewise fractional derivative. The method begins by expressing the unknown functions as expansions in terms of the proposed basis functions. Using these expansions, along with the operational matrix of the piecewise fractional derivative, the original problem is formulated as an optimization problem. Subsequently, the optimization problem is transformed into a system of algebraic equations through the application of the Lagrange multiplier algorithm. Furthermore, an error estimation for the approximate solution is provided to assess the accuracy of the proposed method. Finally, the effectiveness of the numerical algorithm is demonstrated through several illustrative examples.</p>