The newly discovered Yaoertu Cu–Pb–Zn–Ag deposit in the southern Great Xing’an Range (SGXR), NE China, is spatially associated with late Yanshanian intrusions. The Cu mineralization occurs within a fine-grained granite, whereas the Pb–Zn–Ag orebodies are developed within country rocks of the Linxi Formation, and are spatially associated with monzogranite or fine-grained granite. The monzogranite and fine-grained Cu-bearing granite have zircon ages of 137.1 ± 0.4 and 137.4 ± 0.5 Ma, indicating that mineralization occurred in the Early Cretaceous, consistent with the formation of extensive skarn or hydrothermal Pb–Zn–Ag deposits in the SGXR. The monzogranite is enriched in SiO₂ (69.91–67.87 wt%) and Na₂O + K₂O (8.43–7.92 wt%), contains 15.20–14.85 wt% Al₂O₃, and has a mean A/CNK value of 1.01, indicating the monzogranites are weakly-peraluminous high-K calc-alkaline granites. The fine-grained granites contain 77.18–75.14 wt% SiO₂, 5.44–4.73 wt% K₂O, 13.14–12.16 wt% Al₂O₃, 0.62–0.52 wt% CaO, and belong to the high-K calc-alkaline series. The monzogranite is enriched in light rare earth elements (REEs), exhibits fractionation of light over heavy REEs (LREE/HREE = 10.58–9.78), and has Eu/Eu* values of 0.74–0.61, whereas the fine-grained granite has LREE/HREE of 8.34–7.07 and more marked negative Eu anomalies (Eu/Eu* = 0.17–0.11). Zircon δ¹⁸O values in the monzogranite range from 6.61‰ to 6.87‰, and from 6.67‰ to 7.14‰ in the fine-grained Cu-bearing granite. The chemical composition and zircon Hf–O isotopic data suggest that the Early Cretaceous granites are formed by mixing between the juvenile crust and mantle-derived materials. Post-orogenic extensional settings related to the closure of the Mongol–Okhotsk Ocean resulted in extensive magmatism and large-scale mineralization.