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The main reason ZnO is attractive for optoelectronic applications is its polarization behavior, which can modify its optical and electronic properties. Here, the polarization of ZnO is highly dependent on its structure and morphology. We study the polarization behavior of ZnO with different structures and morphology. A seedless ZnO nanocolumnars (ZnO NCs) array is fabricated using DC-unbalanced magnetron sputtering (DC-UBMS) with further thermal annealing treatment. Thermal annealing transforms the cone-like ZnO NCs to become rod-like ZnO NCs and significantly reduces the intensity of the crystal plane (002). Thermal annealing changes the polarization, where the annealed-ZnO 600°C exhibits the highest polarization that promotes the increase in lattice constant c and crystallite size. We found a football-like polarization response without saturation polarization, which indicates a presence of leakage current and defect on the samples. Interestingly, a ferroelectric characteristic is observed in annealed-ZnO 800°C with lower polarization than the annealed-ZnO 600°C. The origin of ferroelectricity is further investigated using a comprehensive study. This study provides a new understanding of polarization behavior on ZnO NCs, which is the essential key in designing switchable and non-volatile-based devices. [ABSTRACT FROM AUTHOR]