The influence of agitation of a frame impeller on the fluidization performance of Geldart D particles is experimentally and numerically studied in a gas-solid stirred fluidized bed, using a three-dimensional (3D) unsteady computational fluid dynamics (CFD) simulation. The bed pressure drops obtained from simulations are in reasonable agreement with those measured with pressure transducers, which validates the CFD models. The experimental results of the pressure fluctuation and the simulated ones of the solid volume fraction distribution show that Geldart D particles can perform homogeneous fluidization in the presence of the impeller. The homogeneous fluidization regime expands as the minimum bubbling velocity increases with the agitation speed while the minimum fluidizing velocity remains unaffected. In addition, the uniformity of particle velocities that are distributed in the entire fluidized bed is also improved by the agitation of the frame impeller.