Sepsis is a life-threatening complication from infection. The early detection of sepsis pre-hospital is challenging. Early warning scores (EWS) are used in hospitals to identify deteriorating patients. The pre-hospital setting could be a beneficial extension to the use of EWSs. This review aimed to determine whether EWSs can identify patients with sepsis pre-hospital and predict patient outcomes. Bibliographic databases were searched for studies evaluating the pre-hospital use of EWSs. Studies were screened using eligibility criteria. Two studies examined the ability of pre-hospital EWSs to identify patients with critical illness, showing high sensitivity but low specificity. Four studies determined the prognostic effects of the National Early Warning Score (NEWS). The patients identified by NEWS to be high-risk were associated with worse outcomes. This systematic review demonstrated the successful use of EWSs in the pre-hospital setting, in identifying patients most at risk of deterioration and as a useful tool for decision-making.