This paper proposes a practical sampled-data I-P controller design for integrating processes. The controller structure, derived from model predictive control theory, is a simple I-P controller. Application to predictive functional control (PFC) is also derived. The proposed controller was obtained by converting the integrating process model to a one-step-ahead model predictive controller. In this controller, the proportional term suppresses changes in the controlled variable, and the integral term determines speed to eliminate offset. This controller is suitable mainly for sampled-data control systems with a long sampling period, because it can avoid setting excessively high proportional gain. Simulation on a typical integrating process demonstrated the effectiveness of the proposed controller. Finally the proposed sampled-data I-P controller was successfully applied to an actual plant having an extremely slow process response.