Background: This study aimed to evaluate the predictive value of N-terminal pro-brain natriuretic peptide (NT-proBNP) for venoarterial extracorporeal membrane oxygenation (VA-ECMO)-assisted clinical outcomes in adult patients with cardiogenic shock (CS). Methods: Our study included the demographic information and clinical data of 77 CS patients who underwent VA-ECMO-assisted therapy in our center between January 2016 and January 2021. The prognostic value of NT-proBNP in these patients was assessed. Results: Statistical analyses were performed using the chi-square or Fisher's exact tests. Among the study participants, the highest NT-proBNP values after VA-ECMO assistance were observed in CS patients who had died versus those undergoing rehabilitation (21,439.62 vs. 13,568.26 pg/mL). Mean NT-proBNP values at the time of ECMO weaning (18,170.95 vs. 8472.8 pg/mL) and before discharge (22,183.35 vs. 5646.197 pg/mL) were higher in the death group. Age, sepsis-related organ failure assessment (SOFA) scores, creatinine, platelet, urea nitrogen, total bilirubin, and lactic acid levels; mean arterial pressure; creatinine level at the point of ECMO weaning, NT-proBNP value before discharge, percentage of left ventricular ejection fraction were reliable predictors of mortality. The area under the receiver operating characteristic curve (AUC–ROC) was >0.70 (p < 0.05). The AUC–ROC of the pre-discharge NT-proBNP was 0.873; these NT-proBNP values had the best predictive ability regarding patient death. Conclusion: Among CS patients who received VA-ECMO assistance, NT-proBNP values at each assistance point had important patient-related diagnostic and predictive values. Pre-discharge NT-proBNP values were the best predictors of patient prognosis.