Immune checkpoint inhibitors (ICIs) have revolutionized lung cancer treatment, yet resistance remains a challenge. Co-inhibition of PD-1/PD-L1 and TGF-β shows promise but faces limited efficacy and systemic toxicity. We developed gelatinase-responsive nanoparticles (GPNPs) delivering anti-PD-1 antibody (αPD-1) and TGF-β receptor I inhibitor galunisertib (Gal). GPNPs effectively inhibit tumor progression without observed side effects. Immune profiling by cytometry assay reveals robust recruitment of both activated and exhausted tumor-infiltrating lymphocytes (TILs) and macrophages. Transcriptomic analysis indicates extracellular matrix modulation, supported by reduced collagen deposition and αSMA expression. Fate mapping demonstrates attenuation of Pdgfrα fibroblast transition to αSMA myofibroblasts, potentially reversing "immune-exclusive" status. This study validates GPNPs as a promising lung cancer immunotherapy platform, offering mechanistic insights for clinical translation and therapeutic enhancement.