Voltage-gated potassium (KV) currents, subdivided into rapidly inactivating A-type currents (IA) and slowly inactivating delayed rectifier currents (IK), play a fundamental role in modulating pain by controlling neuronal excitability. The effects of Honokiol (Hon), a natural biphenolic compound derived from Magnolia officinalis, on KV currents were investigated in freshly isolated mouse dorsal root ganglion neurons using the whole-cell patch clamp technique. Results showed that Hon inhibited IA and IK in concentration-dependent manner. The IC50 values for block of IA and IK were 30.5 and 25.7 µM, respectively. Hon (30 µM) shifted the steady-state activation curves of IA and IK to positive potentials by 17.6 and 16.7 mV, whereas inactivation and recovery from the inactivated state of IA were unaffected. These results suggest that Hon preferentially interacts with the active states of the IA and IK channels, and has no effect on the resting state and inactivated state of the IA channel. Blockade on K+ channels by Hon may contribute to its antinociceptive effect, especially anti-inflammatory pain.