Despite significant advancements in oncology, cancer remains a leading global health burden, necessitating innovative therapeutic strategies. Here, we present a novel carrier-free tumor-targeted nanomedicine system (DPA NPs) for tumor-targeted chemoimmunotherapy, formed by self-assembly of a conjugate synthesized with doxorubicin (DOX), tumor-homing peptide iRGD, matrix metalloproteinase 2 enzyme responsive peptide (MMP2), and adjuvant monophosphoryl lipid A (MPLA). The results demonstrated that DPA NPs exhibited a stable unique 3D nanostructure with tumor microenvironment (TME)-responsive properties. DPA NPs could efficiently deliver DOX to tumor cells, inducing immunogenic cell death (ICD) and simultaneously triggering tumor specific immune response. Meanwhile, MPLA amplified the anti-tumor immunity, significantly inhibiting tumor growth and metastasis. When combined with immune checkpoint inhibitors (ICIs), DPA NPs further enhanced the therapeutic outcomes in a B16 melanoma model, demonstrating remarkable suppression of tumor growth, metastasis inhibition and recurrence prevention. Mechanistic investigations across multiple biological hierarchies conclusively further confirmed the synergistic therapeutic effect. This study demonstrated that DPA NPs provide a precise, multifunctional nanoplatform for tumor-targeted combination therapy, highlighting their potential for clinical translation in cancer treatment.