The present study aimed to investigate the effects of (R)-(−)-1-isothiocyanato-6-(methylsulfinyl)-hexane [(R)-6-HITC], the major isothiocyanate present in wasabi, in an ex vivo model of inflammation using lipopolysaccharide-stimulated murine peritoneal macrophages. (R)-6-HITC improved the immune response and mitigated oxidative stress, which involved suppression of reactive oxygen species, nitric oxide, and pro-inflammatory cytokines (IL-1β, IL-6, IL-17, IL-18, and TNF-α) production and downregulation of pro-inflammatory enzymes such as inducible nitric oxide synthase, COX-2, and mPGES-1. In addition, (R)-6-HITC was able to activate the Nrf2/HO-1 axis while simultaneously inhibiting key signaling pathways, including JAK2/STAT3, mitogen-activated protein kinases, and canonical and noncanonical inflammasome pathways, orchestrating its potent immunomodulatory effects. Collectively, these findings demonstrate the potential of (R)-6-HITC as a promising nutraceutical for the management of immuno-inflammatory diseases and justify the need for further in vivo validation studies.