Background: To achieve early reperfusion therapy for ST-elevation myocardial infarction (STEMI), proper and prompt patient transportation and activation of the catheterization laboratory are required. We investigated the efficacy of prehospital 12-lead electrocardiogram (ECG) acquisition and destination hospital notification in patients with STEMI. Methods and Results: This is a systematic review of observational studies. We searched the PubMed database from inception to March 2020. Two reviewers independently performed literature selection. The critical outcome was short-term mortality. The important outcome was door-to-balloon (D2B) time. We used the GRADE approach to assess the certainty of the evidence. For the critical outcome, 14 studies with 29,365 patients were included in the meta-analysis. Short-term mortality was significantly lower in the group with prehospital 12-lead ECG acquisition and destination hospital notification than in the control group (odds ratio 0.72; 95% confidence interval [CI] 0.61–0.85; P<0.0001). For the important outcome, 10 studies with 2,947 patients were included in the meta-analysis. D2B time was significantly shorter in the group with prehospital 12-lead ECG acquisition and destination hospital notification than in the control group (mean difference −26.24; 95% CI −33.46, −19.02; P<0.0001). Conclusions: Prehospital 12-lead ECG acquisition and destination hospital notification is associated with lower short-term mortality and shorter D2B time than no ECG acquisition or no notification among patients with suspected STEMI outside of a hospital.