Tuning the morphology of heterogeneous catalysts is of paramount importance for the design of efficient processes and requires detailed information on the physicochemical characteristics of the materials. Four micro-/mesoporous composites with different morphologies were synthesized by a dual-templating method using two-step crystallization with different zeolite seed concentrations. This work demonstrates the dependence of selectivity on the catalyst nature in solid-acid alkylation. It was demonstrated that a high concentration of weak acid sites leads to dialkyltoluene products, whereas a high concentration of strong acid sites is beneficial for other side reactions. It was shown that the morphology of catalysts played a crucial role in solid-acid alkylation. The alkylation mechanism defined in this study with different contributions of weak and strong acid sites could provide a route to the development of effective solid-acid catalysts.