Background: Early diagnosis of acute brain injury (ABI) is critical for patients on venoarterial extracorporeal membrane oxygenation (VA-ECMO) to guide anticoagulation strategy; however, neurological assessment in ECMO is often limited by patient sedation. Methods: In this pilot study of adults from June 2018 to May 2019, plasma samples of glial fibrillary acidic protein (GFAP), neurofilament light chain (NFL), and Tau were collected daily after VA-ECMO cannulation and measured using a multiplex platform. Primary outcomes were the occurrence of ABI, assessed clinically, and neurologic outcome, assessed by modified Rankin Scale (mRS). Results: Of 20 consented patients (median age=48.5 years; 55% female), 8 (40%) had ABI and 15 (75%) had unfavorable neurologic outcomes at discharge. 10 (50%) patients were centrally cannulated. The median duration on ECMO was 4.5 days (IQR: 2.5-9.5). Peak GFAP, NFL, and Tau levels were higher in patients with ABI vs. without (AUC = 0.77; 0.85; 0.57, respectively) and in patients with unfavorable vs. favorable neurologic outcomes (AUC = 0.64; 0.59; 0.73, respectively). GFAP elevated first, NFL elevated to the highest degree, and Tau showed limited change regardless of ABI. Conclusion: Plasma biomarkers may facilitate early detection of ABIs in VA-ECMO where neurological exam is limited and assist timely clinical decision-making.