Many researches have been dedicated to the comprehension of the mechanisms underlying the dynamical arrest of gelling systems due to their involvement in several technological fields, from food to biotechnology. The question about a unifying point of view for colloidal gelation, colloidal glass transition and chemical gelation is still unanswered. In the case of high methoxyl pectins (HMP), a widely used gelling agent in food industry, the gel formation is promoted by the presence of cosolutes (sugars or polyols) and low pH. The present investigation regards the structuring kinetics of aqueous HMP solutions containing few percent of pectin and increasing concentration of sucrose, from 0 to 65% w/w, at 20 °C. The aim of the investigation is the understanding of the role of the co-solute on the gelation properties of the polysaccharide, focusing on the structural organization characterizing the final gelled state. Our data suggest that sucrose plays a crucial role in governing the structural characteristics of high methoxyl pectin macroscopic gelation in a way that is extremely sensitive to small co-solute concentration changes. The time evolution of the mechanical properties is in both qualitative and quantitative terms strictly affected by the sucrose presence and the transition from sol to gel state occurs when the excluded volume effects and the attractive interactions are able to create a three-dimensional network by freezing the polymer dynamics, as it occurs in attractive glasses or weakly attractive colloidal dispersions.