Millions of households have cats or dogs as pets, and infections due to bites or scratches are increasing, with the most common pathogens being Pasteurella spp., Bartonella spp., Capnocytophaga spp, and Francisella tularensis. The objective of this study was to describe patients admitted to the intensive care unit (ICU) for infection transmitted by cats or dogs, as well as their outcomes. The retrospective multicentre observational cohort study PETSEPSIS included consecutive adults admitted to 46 ICUs in France between 2009 and 2019 for sepsis due to cat or dog bites and/or caused by any of the four above-listed bacteria. We described their features and outcomes and performed univariate and multivariate analyses to identify factors associated with death. We included 174 patients with a median age of 64 [50–74] years; 58.1% were male. The median SAPS II score was 42 [28–58]. Mechanical ventilation was required in 51.2% of patients, for a median duration of 7 [4–13] days. Vasopressor support was used in 53.5%, renal replacement therapy in 19%, and limb amputation in 3.6% of the patients. The median ICU length of stay was 7 [4–16] days. Hospital mortality was 24.1%. The clinical presentation and severity of sepsis were similar across bacteria, although patients with Pasteurella spp. were older and had more comorbidities. Contact with cats were more often reported for Pasteurella spp. and Bartonella spp. infections and contact with dogs for Capnocytophaga spp. infections. Risk factors for hospital mortality present on ICU admission were older age, smoking, preexisting liver disease, high serum creatinine, and anaemia. Neither the type of micro-organism nor the initial antimicrobial treatment was associated with mortality. This large multicentre study shows that infections transmitted by cats and dogs are infrequent reasons for ICU admission but are associated with substantial morbidity and mortality. Mortality was associated with older age and comorbidities but not with the type of microorganism or initial antibiotic treatment.