The COVID-19 pandemic has changed the university admissions and proficiency testing landscape. One change has been the meteoric rise in use of the fully automated Duolingo English Test (DET) for university entrance purposes, offering test-takers a cheaper, shorter, accessible alternative. This rapid response study is the first to investigate the predictive value of DET test scores in relation to university students' academic attainment, taking into account students' degree level, academic discipline, and nationality. We also compared DET test-takers' academic performance with that of students admitted using traditional proficiency tests. Credit-weighted first-year academic grades of 1881 DET test-takers (1389 postgraduate, 492 undergraduate) enrolled at a large, research-intensive London university in Autumn 2020 were positively associated with DET Overall scores for postgraduate students (adj. r = 0.195) but not undergraduate students (adj. r = -0.112). This result was mirrored in correlational patterns for students admitted through IELTS (n = 2651) and TOEFL iBT (n = 436), contributing to criterion-related validity evidence. Students admitted with DET enjoyed lower academic success than the IELTS and TOEFL iBT test-takers, although sample characteristics may have shaped this finding. We discuss implications for establishing cut scores and harnessing test-takers' academic language development through pre-sessional and in-sessional support.