A series of undrawn and drawn tapes has been prepared from HDPE, as well as, blends consisting of 90% HDPE and 10% ethylene copolymers. The influence of both the molecular irregularity of ethylene copolymers and resultant crystallization behavior on structure and mechanical properties of these blends has been investigated using differential scanning calorimetry, wide- and small-angle X-ray diffraction, mechanical response at small and large strains, and dynamic mechanical thermal analysis. The tensile drawing study of undrawn tapes shows enhanced strain hardening and a consistent reduction in natural, as well as, maximum achievable draw ratio with an increase in molecular irregularity of ethylene copolymers. It has been confirmed that blends are partially miscible in the amorphous, as well as, in the crystalline phase through cocrystallization. The lateral crystallite thicknesses, crystallinity, and amorphous phase orientation of blends consistently decreases with an increase in molecular irregularity of ethylene copolymers because of a large-scale change in crystallization and drawing behavior of HDPE component in the blends. There is a distinct possibility that the molecular network exerts an important influence on physical and mechanical properties of undrawn and drawn tapes.