β‐arrestins 1 and 2 are ubiquitously expressed proteins that alter signalling by G‐protein‐coupled receptors. β‐arrestin 2 plays an important role as a signalling adaptor and scaffold in regulating cellular inflammatory responses. We hypothesized that β‐arrestin 2 is a critical modulator of inflammatory response in experimental sepsis. β‐arrestin 2(−/−) and wild‐type (WT) mice were subjected to caecal ligation and puncture (CLP). The survival rate was significantly decreased (P < 0·05) in β‐arrestin 2(−/−) mice (13% survival) compared with WT mice (53% survival). A second group of mice were killed 18 hr after CLP for blood, peritoneal lavage and tissue sample collection. CLP‐induced plasma interleukin (IL)‐6 was significantly increased 25 ± 12 fold and caecal myeloperoxidase (MPO) activity was increased 2·4 ± 0·3 fold in β‐arrestin 2(−/−) compared with WT mice. β‐arrestin 2(−/−) mice exhibited more severe lung damage and higher bacterial loads compared with WT mice post CLP challenge as measured by histopathology and colony‐forming unit count. In subsequent experiments, splenocytes, peritoneal macrophages and bone marrow‐derived macrophages (BMDMs) were isolated and cultured from β‐arrestin 2(−/−) and WT mice and stimulated in vitro with lipopolysaccharide (LPS). Tumour necrosis factor (TNF)‐α, IL‐6 and IL‐10 production induced by LPS was significantly augmented (2·2 ± 0·2 fold, 1·8 ± 0·1 fold, and 2·2 ± 0·4 fold, respectively; P < 0·05) in splenocytes from β‐arrestin 2(−/−) mice compared with WT mice. The splenocyte response was different from that of peritoneal macrophages or BMDMs, which exhibited no difference in TNF‐α and IL‐6 production upon LPS stimulation between WT and β‐arrestin 2(−/−) mice. Our data demonstrate that β‐arrestin 2 functions to negatively regulate the inflammatory response in polymicrobial sepsis.