This study investigated the influence of surface-inactive carbohydrates on association characteristics of amphiphilic mung bean protein hydrolysate (MPH) and asiatic acid (AA) in aqueous suspension (11.72–11.94% total solids). The carbohydrates investigated were trehalose, maltodextrin, mixed trehalose–maltodextrin and mixed maltodextrin–starch. The presence of low-molecular-weight carbohydrates enhanced micellisation of AA to form micrometre-sized particles due to depletion flocculation. Nonetheless, the presence of starch retained the submicrometre size of AA. In contrast, the presence of starch enhanced self-association of MPH via segregative phase separation. However, the mixed suspensions containing MPH, AA and carbohydrate in a ratio of 1:0–0.072:2.34, respectively, retained particle sizes of around 300 nm regardless of the carbohydrate used. It was found that the MPH–AA co-aggregates were stable against the osmotic effect of carbohydrates. The results suggest that carbohydrates regulated the aggregate size and surface hydrophobic region of MPH and MPH–AA by controlling surface-induced aggregation.