An excessive inflammatory response in terminal airways, alveoli, and the lung interstitium eventually leads to pulmonary hypertension and chronic obstructive pulmonary disease. Proinflammatory cytokine interleukin-17A (IL-17A) has been implicated in the pathogenesis of pulmonary inflammatory diseases. MLN4924, an inhibitor of NEDD8-activating enzyme (NAE), is associated with the treatment of various types of cancers, but its role in the IL-17A-mediated inflammatory response has not been identified. Here, we report that MLN4924 can markedly reduce the expression of proinflammatory cytokines and chemokines such as IL-1β, IL-6, and CXCL-1 and neutrophilia in a mouse model of IL-17A adenovirus-induced pulmonary inflammation. MLN4924 significantly inhibited IL-17A-induced stabilization of mRNA of proinflammatory cytokines and chemokines in vitro. Mechanistically, MLN4924 significantly blocked the activation of MAPK and NF-κB pathways and interfered with the interaction between ACT1 and tumor necrosis factor receptor-associated factor proteins (TRAFs), thereby inhibiting TRAF6 ubiquitination. Taken together, our data uncover a previously uncharacterized inhibitory effect of MLN4924 on the IL-17A-mediated inflammatory response; this phenomenon may facilitate the development of MLN4924 into an effective small-molecule drug for the treatment of pulmonary inflammatory diseases.