Diol functionalization with acetals in carbohydrates and polyols is ubiquitously used in protection chemistry and in the manufacture of several platform chemicals. However, the selective functionalization of molecules where multiple acetalization reactions can occur typically involves multiple protection/deprotection steps. Here, we show that zeolites can be used to size‐selectively acetalize sugars and polyols in a single step, and we demonstrate the potential of this approach for producing functional chemicals and materials. We show that high selectivity is dependent on effective pore confinement, which is achieved by a careful pairing of the substrate size and the zeolite morphology. This zeolite‐catalyzed strategy exhibited consistently good‐to‐excellent yields (70%–95%) of novel polyol/sugar monoacetals, notably offering an easy route to bio‐based amphiphiles. These resulting xylose‐based surfactants exhibited similar or superior surface activity and, remarkably, hard‐water resistance compared to their nonrenewable ethoxylated analogues, which illustrates the potential for practical applications of this approach.