The CsI-based scintillators have been widely used for X-or gamma-ray detections. It has been known that columnar scintillators favor the detections with higher efficiency and spatial resolution. In this paper, we report a facile and low-cost method to fabricate submicron nanoscale CsI columns. We integrated the thermodynamic calculations, positive chamber design, mold design, electrochemical bath design, anodization process, and solidification techniques to fabricate such submicron CsI columns. When the CsI melt is confined to AAO channels with a high aspect ratio, stable CsI columns solidified with smooth surfaces, and free of dendrites or grain boundaries. Different solidification approaches have been attempted, including mechanical injection in vacuum under a negative pressure, injection at 1 atm, 3 atm and 25 atm using Ar gas only, and mechanical injection with 1.6 atm Ar pressure. The mechanical injection or high-pressure Ar injection at 25 atm produced good filling of CsI melt into AAO channels. Such CsI columns inside the smooth AAO walls enable the highenergy radiation detection with high light emission for pixelated scintillator applications.