TAK1, a serine/threonine kinase, has been implicated as a key mediator downstream of pattern recognition receptors and pro-inflammatory cytokine receptors that enables the provocation of innate immune responses such as inflammation; however, little is known about its potential role in limiting inflammatory responses in macrophages. Using genetic and pharmacological approaches, here we show that TAK1 in macrophages is involved in negatively regulating inflammation by blocking a cell death pathway. Mice with conditional deletion of TAK1 in macrophages (TAK1ΔM) on a TNFα-deficient background (TAK1ΔM x TNFα-/-) displayed sterile inflammation prominently in the liver and peritoneal cavity, in which resident macrophages virtually disappeared. Remarkably, macrophages from TAK1ΔM x TNFα-/- mice exhibited massive cell death in response to lipopolysaccharide (LPS) or poly(I:C), which took place in a manner dependent on the TLR-mediated activation of Caspase-8. Despite the fact that TNFα is known as a lethal factor for systemic inflammation such as septic shock, TAK1ΔM x TNFα-/- mice were much more susceptible to LPS-induced endotoxin shock than wild-type mice, implying an event that is independent of the physiological action of TNFα. Importantly, we found that the symptom was presumably caused by macrophage cell death in response to LPS. Collectively, our data unveiled a novel aspect of TAK1 as a key signaling checkpoint in preventing cell death, which gives rise to inflammatory responses.