Ganoderma lucidum, a fungus of significant scientific interest that encompasses a diverse array of bioactive compounds, has been extensively investigated for its potential health-promoting and disease-preventing properties. Ganodermanontriol, a triterpenoid, is the principal active component contributing to its biological activities. This study aimed to explore the anti-inflammatory properties of ganodermanontriol and to evaluate its potential as a functional ingredient. The expression of inflammatory mediators, including tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS), and nitric oxide (NO) production was significantly inhibited in ganodermanontriol (1.25–5 μg/mL)-treated compared to that of untreated lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Additionally, the phosphorylation of mitogen-activated protein kinases (MAPK), specifically p38 and c-Jun N-terminal kinase (JNK), was markedly inhibited in ganodermanontriol (3–5 μg/mL)-treated cells. These findings indicate that ganodermanontriol possesses significant potential as both a prophylactic and therapeutic agent for immune-related disorders, owing to its ability to modulate inflammatory responses.