Coixol, a plant polyphenol extracted from coix (Coix lachryma-jobi L.var.ma-yuen Stapf), has not been investigated for its anti-inflammatory effect. In this study, using a lipopolysaccharide (LPS)-induced macrophage cell model, we observed that coixol can effectively reduce the expression of interleukin (IL)-1β, IL-6, IL-18, tumor necrosis factor (TNF)-α, nitric oxide (NO), inducible nitric oxide synthases (iNOS), and cyclooxygenase (COX)-2, but had no effect on the expression of the anti-inflammatory mediator IL-10. Furthermore, we found that coixol inhibits mitogen-activated protein kinases (MAPKs), nuclear transcription factor κ B (NF-κB) pathways, and NOD-like receptor protein (NLRP) 3 inflammasome activation. In conclusion, the present study demonstrates that coixol exerts certain anti-inflammatory effects by inhibiting the expression of pro-inflammatory mediators in vitro. The mechanism of this effect was in part related to its ability to inhibit the activation of NF-κB, MAPKs pathways, and NLRP3 inflammasome.