Bacterial and viral infections in the lungs promote an adaptive immunity response involving inflammasome formation and activation in macrophages. The most severe infections can lead to acute respiratory distress syndrome (ARDS), a devastating illness with high mortality and few therapeutic options. Inflammasome signaling involves both a priming stimulus to assemble the components and a second activation signal that causes cleavage and release of pro-inflammatory mediators such as IL-1β. The activation step is dependent upon a decrease in intracellular K+, but the identity of the efflux channel is unclear. In this study we investigated the potential role of a two-pore potassium channel, TREK1, in inflammasome signaling. Mice that were deficient in TREK1 expression (TREK1-/-) exhibited decreased lung injury compared with wild type (wt) mice when exposed to aerosolized LPS, a potent inflammsome stimulus. To evaluate inflammasome signaling, we used bone marrow-derived macrophages (BMDMs) and alveolar macrophages (AMs) exposed to LPS for priming followed by ATP for activation. Expression of NLRP3 increased in BMDMs from wt mice following LPS priming, and this was diminished in TREK1-/- BMDMs and in wt BMDMs treated with a specific TREK1 inhibitor (Spadin). AMs from TREK1-/- secreted significantly less IL-1β compared with wt AMs following LPS+ATP. Intracellular K+ (measured using Asante green as an indicator) was increased in TREK1-/- compared with wt BMDMs following LPS treatment. Wt BMDMs treated with Spadin exhibited intracellular K+ similar to untreated wt, while the TREK1 activator BL1249 promoted decreased K+. When cells were subsequently treated with ATP, there was a rapid decrease in intracellular K+ in wt BMDMs that was diminished by TREK1 inhibition. There was a much larger decline in intracellular K+ in TREK1-/- BMDMs following ATP, but the concentration remained higher than that in wt BMDMs. These results suggest that TREK1 regulates NLRP3 inflammasome priming and activation through mechanisms involving K+ efflux.