ImportanceSepsis screening is recommended among hospitalized patients but is supported by limited evidence of effectiveness.ObjectiveTo evaluate the effect of electronic sepsis screening, compared with no screening, on mortality among hospitalized ward patients.Design, Setting, and ParticipantsIn a stepped-wedge, cluster randomized trial at 5 hospitals in Saudi Arabia, 45 wards (clusters) were randomized into 9 sequences, 5 wards each, to have sepsis screening implemented at 2-month periods. The study was conducted between October 1, 2019, and July 31, 2021, with follow-up through October 29, 2021.InterventionAn electronic alert, based on the quick Sequential Organ Failure Assessment score, was implemented in the electronic medical record in a silent mode that was activated to a revealed mode for sepsis screening.Main Outcomes and MeasuresThe primary outcome was 90-day in-hospital mortality. There were 11 secondary outcomes, including code blue activation, vasopressor therapy, incident kidney replacement therapy, multidrug-resistant organisms, and Clostridioides difficile.ResultsAmong 60 055 patients, 29 442 were in the screening group and 30 613 in the no screening group. They had a median age of 59 years (IQR, 39-68), and 30 596 were male (51.0%). Alerts occurred in 4299 of 29 442 patients (14.6%) in the screening group and 5394 of 30 613 (17.6%) in the no screening group. Within 12 hours of the alert, patients in the screening group were more likely to have serum lactate tested (adjusted relative risk [aRR], 1.30; 95% CI, 1.16-1.45) and intravenous fluid ordered (aRR, 2.17; 95% CI, 1.92-2.46) compared with those in the no screening group. In the primary outcome analysis, electronic screening resulted in lower 90-day in-hospital mortality (aRR, 0.85; 95% CI, 0.77-0.93; P < .001). Screening reduced vasopressor therapy and multidrug-resistant organisms but increased code blue activation, incident kidney replacement therapy, and C difficile.Conclusions and RelevanceAmong hospitalized ward patients, electronic sepsis screening compared with no screening resulted in significantly lower in-hospital 90-day mortality.Trial RegistrationClinicalTrials.gov Identifier: NCT04078594