Shunt active power filters have been widely used for power quality improvement. With the advancement in artificial intelligence techniques, the applications of fuzzy logic-based control systems have increased manifolds. This paper proposes a reduced rule fuzzy logic controller (FLC) in the voltage control loop of a shunt active power filter (APF), which is approximating a conventional large rule FLC. The difference between the controlled outputs of two controllers is compensated by proposed compensating factors. The dynamic response and harmonic compensation performance of proposed 4-rule approximated fuzzy logic controller (AFLC) is compared with 25-rule FLC. A three-phase shunt APF is used for harmonic and reactive power compensation. The proposed scheme is tested with randomly varying single and multiple non-linear loads. The simulation results presented under transient and steady-state conditions confirm that the proposed 4-rule AFLC efficiently approximates the 25-rule FLC. The proposed control methodology takes less computational time and computational memory as the numbers of rules are reduced significantly.