Background The benefit of intravenous thrombolysis is time dependent. It remains unclear, however, whether dramatic shortening of door-to-needle time (DNT) among different types of hospitals nationwide does not compromise safety and still improves outcome. Methods and Results Multifaceted intervention to shorten DNT was introduced at a national level, and prospectively collected data from a registry between 2004 and 2019 were analyzed. Generalized estimating equation was used to identify the association between DNT and outcomes independently from prespecified baseline variables. The primary outcome was modified Rankin score 0 to 1 at 3 months, and secondary outcomes were parenchymal hemorrhage/intracerebral hemorrhage (ICH), any ICH, and death. Of 31 316 patients treated with intravenous thrombolysis alone, 18 861 (60%) had available data: age 70 +/- 13 years, National Institutes of Health Stroke Scale at baseline (median, 8; interquartile range, 5-14), and 45% men. DNT groups 0 to 20 minutes, 21 to 40 minutes, 41 to 60 minutes, and >60 minutes had 3536 (19%), 5333 (28%), 4856 (26%), and 5136 (27%) patients. National median DNT dropped from 74 minutes in 2004 to 22 minutes in 2019. Shorter DNT had proportional benefit: it increased the odds of achieving modified Rankin score 0 to 1 and decreased the odds of parenchymal hemorrhage/ICH, any ICH, and mortality. Patients with DNT <= 20 minutes, 21 to 40 minutes, and 41 to 60 minutes as compared with DNT >60 minutes had adjusted odds ratios for modified Rankin score 0 to 1 of the following: 1.30 (95% CI, 1.12-1.51), 1.33 (95% CI, 1.15-1.54), and 1.15 (95% CI, 1.02-1.29), and for parenchymal hemorrhage/ICH: 0.57 (95% CI, 0.45-0.71), 0.76 (95% CI, 0.61-0.94), 0.83 (95% CI, 0.70-0.99), respectively. Conclusions Ultrashort initiation of thrombolysis is feasible, improves outcome, and makes treatments safer because of fewer intracerebral hemorrhages. Stroke management should be optimized to initiate thrombolysis as soon as possible optimally within 20 minutes from arrival to a hospital.