Urinary tract infection (UTI) is a prevalent bacterial infection, predominantly caused by uropathogenic Escherichia coli (UPEC). Severe UTIs can lead to kidney damage, which is closely associated with increased infiltration of M1-type macrophages. DNAX-activating protein of 12 kD (DAP12) is extensively expressed in myeloid cells and natural killer (NK) cells, and it can interact with TREM receptors to mediate various immune responses. Our study revealed that DAP12 deletion significantly mitigated kidney injury induced by UPEC infection, a phenomenon strongly correlated with reduced macrophage infiltration. Further investigation demonstrated that DAP12 directly regulates the polarization of macrophages during UPEC infection. In an endotoxin shock model induced by LPS derived from E. coli, DAP12 deficiency similarly decreased mortality and inhibited LPS-induced macrophage polarization in mice. Collectively, these findings suggest that the TREM1-DAP12 signaling pathway plays a critical role in kidney injury caused by UPEC infection, indicating that this pathway could serve as a novel therapeutic target for treating UPEC-induced kidney damage.