IMPORTANCE Although several studies have demonstrated an improvement in mortality for injured adults who receive whole-body computed tomography (WBCT), it is unclear whether children experience the same benefit. OBJECTIVE To determine whether emergent WBCT is associated with lower mortality among children with blunt trauma compared with a selective CT approach. DESIGN, SETTING, AND PARTICIPANTS A retrospective, multicenter cohort study was conducted from January 1, 2010, to December 31, 2014, using data from the National Trauma Data Bank on children aged 6 months to 14 years with blunt trauma who received an emergent CT scan in the first 2 hours after emergency department arrival. Data analysis was conducted from February 2 to December 29, 2017. EXPOSURES Patients were classified as having WBCT if they received CT head, CT chest, and CT abdomen/pelvis scans in the first 2 hours and as having a selective CT if they did not receive all 3 scans. MAIN OUTCOMES AND MEASURES The primary outcome was in-hospital mortality in the 7 days after ED arrival. To adjust for potential confounding, propensity score weighting was used. Subgroup analyses were performed for those with the highest mortality risk (ie, occupants and pedestrians involved in motor vehicle crashes, children with a Glasgow Coma Scale score lower than 9, children with hypotension, and those admitted to the intensive care unit). RESULTS Of the 42 912 children included in the study (median age [interquartile range], 9 [5-12] years; 27 861 [64.9%] boys), 8757 (20.4%) received a WBCT. Overall, 405 (0.9%) children died within 7 days. After adjusting for the propensity score, children who received WBCT had no significant difference in mortality compared with those who received selective CT (absolute risk difference, −0.2%; 95% CI, −0.6% to 0.1%). All subgroup analyses similarly showed no significant association between WBCT and mortality. CONCLUSIONS AND RELEVANCE Among children with blunt trauma, WBCT, compared with a selective CT approach, was not associated with lower mortality. These findings do not support the routine use of WBCT for children with blunt trauma.