Carbohydrates are intriguing biomolecules possessing diverse biological activities including immune stimulating capability. However, their biomedical applications have been limited by the complex and heterogeneous structures. Here, we have utilized a self-assembling glycopeptide conjugate (GPC) system to produce uniform nanoribbons appending homogeneous oligosaccharides in multivalency. This system successfully translates the non-trivial structural differences of oligomannoses into varied binding affinities to C-type lectin receptors (CLRs). We have shown that GPCs could promote the CLR-mediated endocytosis of ovalbumin (OVA) antigen, and two mannotriose-modified peptides F3m2 and F3m5 exhibit potent activity in inducing antigen-presenting cell maturation, as indicated by increased CD86 and MHCII expression. In vivo studies demonstrate that GPCs, combined with OVA antigen, significantly enhanced OVA-specific antibody production. Specifically, F3m2 and F3m5 exhibited the highest immunostimulatory effects, eliciting both Th1- and Th2-biased immune responses, and promoting differentiation of CD4+ and CD8+ T cells. These findings highlight the potential of GPCs as vaccine adjuvants, and showcase their versatility in exploiting the biological functions of carbohydrates.