Abstract: Ischemia-reperfusion injury (IRI) remains an unavoidable challenge in liver surgery, with macrophages playing a critical role in its pathogenesis. However, the mechanisms by which macrophages regulate the pathogenesis of IRI are not well understood. Through a target-guided screening approach, we identified a small 3 kDa peptide (SjDX5-271) from various schistosome egg-derived peptides that induced M2 macrophage polarization. SjDX5-271 treatment protected mice against liver IRI by promoting M2 macrophage polarization, and this protective effect was abrogated when the macrophages were depleted. Transcriptomic sequencing showed that the TLR signaling pathway was significantly inhibited in macrophages from the SjDX5-271 treatment group. We further identified that SjDX5-271 promoted M2 macrophage polarization by inhibiting the TLR4/MyD88/NF-κB signaling pathway and alleviated hepatic inflammation in liver IRI. Collectively, SjDX5-271 exhibited some promising therapeutic effects in IRI and represented a novel therapeutic approach, potentially applicable to other immune-related diseases. The current study demonstrates the potential of new biologics from the parasite, enhances our understanding of host-parasite interplay, and provides a blueprint for future therapies for immune-related diseases.