We demonstrate herein the ZIF‐8‐only‐mediated catalysis of the cyclodimerization of epichlorohydrin to 2,5‐bis(chloromethyl)‐1,4‐dioxane in the absence of co‐catalyst and solvent. The easy handling and economic aspects of ZIF‐8, in addition to the one‐step reaction to produce the cyclodimer, make this catalyst attractive even for industry. It has been clearly illustrated that the nature of the method used to synthesize ZIF‐8 affected the yields of the cyclodimers. Specifically, the method employed to produce ZIF‐8 directly influences the amount of crystal structural defects, which in turn impacts their performance as catalysts. To emphasize the role of defects, other physical properties, such as surface area and particle size, were controlled during the synthesis of the ZIF‐8 catalysts. Remarkably, the amount of structural defects was quantified by temperature program desorption analysis.