AbstractThe clinical efficacy of personalized cancer vaccines still needs to be improved due to their insufficient immune effect. The development of innovative adjuvants and lymph node‐targeted delivery systems is the key to improving the clinical efficacy of personalized vaccines. However, there is still a lack of an adjuvant delivery system that is simple in preparation and capable of mass production and integrates adjuvant and lymph node targeted delivery functions. Here, this work reports that a simple dendrimer polypeptide (KK2DP7) nanoparticle enhances the immune efficacy of an OVA/neoantigen‐based vaccine. Due to its multiple functions as a delivery vehicle, immune adjuvant, and facilitator of dendritic cell migration, KK2DP7 efficiently increases the efficiency of antigen uptake and cross‐presentation by antigen‐presenting cells (APCs) and delivers antigens to lymph nodes via APCs. Strikingly, the antitumor effect of KK2DP7/OVA is superior to that of commonly used adjuvants such as poly(I:C), CpG, and aluminum adjuvant combined with OVA. Furthermore, KK2DP7/OVA combined with anti‐PD‐1 antibody is able to prevent tumor recurrence in a postoperative recurrent tumor model. Thus, KK2DP7‐based cancer vaccines alone or in combination with immune checkpoint blockade therapies to treat tumors or postoperative tumor recurrence are a powerful strategy to enhance antitumor immunity.