Abstract This chapter presents the design of a fuzzy logic controller (FLC) for boost-type power factor corrector. A systematic off-line design approach using the genetic algorithm to optimize the input and output fuzzy subsets in the FLC is proposed. Apart from avoiding complexities associated with nonlinear mathematical modeling of switching converters, circuit designers do not have to perform time-consuming procedures of fine-tuning the fuzzy rules, which require sophisticated experience and intuitive reasoning as in many classical fuzzy-logic-controlled applications. Optimized by a multi-objective fitness function, the proposed control scheme integrates the FLC into the feedback path and a linear programming rule on controlling the duty time of the switch for shaping the input current waveform, making it unnecessary to sense the rectified input voltage. A 200-W experimental prototype has been built. The steady-state and transient responses of the converter under a large-signal change in the supply voltage and in the output load are investigated.