We investigated the effects of poling conditions on the piezoelectric performance of potassium sodium niobate [(K,Na)NbO3, KNN]/polymer composites, to obtain their unsteady energy harvesting potential. KNN nanoparticle/polymer composites were designed and fabricated and the poling condition test was performed. The composites were polarized using the corona poling method for various poling conditions and then the piezoelectric coefficient d33 was measured. It was found that piezoelectricity does not decrease over days. Scanning electron microscopic observations were conducted to study the distribution of the nanoparticles in the matrix. Meanwhile, the microstructure of the composites was studied by X-ray diffraction. Unsteady wind energy harvesting tests were accomplished to investigate the output voltage characteristics in the KNN nanoparticle/polymer composites in unsteady winds. The study represents an important step in developing flexible energy harvesters with stable performance.