Various kinds of macromonomers have been specially designed and systematically synthesized for their application to polymer gel electrolyte hosts. Poly(alkylene oxide) was selected for the polymer backbone, and its chain ends were modified to form acryloyl groups. The gel electrolytes were prepared by cross-linking the macromonomers dissolved in a liquid electrolyte of 1 mol/L LiClO4 in propylene carbonate. Mechanical and electrochemical properties of the gel electrolytes were explored in detail. The results of tensile strength, elongation at break, and shear modulus measurements suggested that a favorable cross-linking reaction proceeded in the polymer gel electrolytes. Cross-linked macromonomer films showed excellent swelling characteristics for liquid-electrolyte uptake and this led to stable liquid retention. High ionic conductivity was attained while keeping sufficient mechanical strength, reflecting stability of the liquid uptake process. The potential stability windows of the gel electrolytes, determined by cyclic voltammetry measurements, were as high as 4.5 V vs. Li/Li+.