The crystallization studies revealed that the high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) formed strong cocrystalline mass when they were melt blended in a single screw extruder. The progress of crystallization was observed through a small-angle light scattering instrument, scanning electron microscope, and differential scanning calorimeter. Analysis showed that these constituents followed individual nucleation and combine growth of crystallites in blends. The growth of crystallites all through the blend compositions were two-dimensional. Interestingly, the crystallites resembled each other for a particular blend composition; however, they differ widely as the composition changes. The rate of crystallization depends greatly to the number of crystallites and their interfacial boundary in contact with the amorphous phase pool. The t(1/2) and percentage of crystallinity showed a mutually exclusive trend and were seen to be varied in the following three regions of blend composition : the HDPE-rich, the LLDPE-rich, and the middle region of blend composition. The percentage of crystallinity decreases in both the HDPE-rich and LLDPE-rich blends, and it showed a plateau value in the middle region of blend composition. The t(1/2) showed opposite trend to that of % crystallinity.