Plant proteins are limited in food applications due to their poor solubility and interfacial properties. Therefore, improving their functional properties through glycosylation modification is of great significance. This study aimed to investigate the effects of different molecular structures on the glycosylation structure and functional properties of mung bean protein. Mung bean protein was subjected to glycosylation with Lactose (Lac) and 2′-Fucosyllactose (2′-FL) at 65 °C and a relative humidity of 74%. The degree of grafting (DG) was used as an evaluation indicator to determine the optimal protein-to-sugar ratio and reaction time, and the glycosylation products with the highest DG were selected for structural characterization and functional property analysis.The results showed that the maximum DG of grafting reached 42.67% after 10 h for the Lac system and 39.11% after 12 h for the 2′-FL system, with a significant difference between the two systems. When the sugar-to-protein mass ratio was 2:1, both systems exhibited the highest DG. SDS-PAGE results showed that glycosylated products exhibited high-molecular-weight aggregated bands, further confirming the covalent binding between proteins and sugars. Meanwhile, the increased particle size, higher absolute value of ζ-potential, and changes in secondary structure indicated that glycosylation significantly altered the structure of mung bean protein and improved its solubility, emulsifying properties, and foaming properties. Specifically, the foaming capacity of the Lac system increased from 67.40% to 89.93%, indicating stronger interfacial activity, while the foam stability of the 2′-FL system increased from 51.87% to 80.13%, showing a more pronounced improvement in interfacial stability. This study provides a theoretical basis for the structural optimization of plant proteins and the application of functional oligosaccharides in plant protein functionalization.