Previous studies have suggested that the D-dimer to fibrinogen ratio (DD/Fg) could be a potential predictor for deep vein thrombosis, pulmonary embolism, and stroke severity. However, the association between plasma DD/Fg and functional outcome following acute ischemic stroke (AIS) has been unclear. Our study followed the STROBE guideline and used a prospective cohort design to investigate this association. Patients with AIS were recruited, and the National Institute of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) were assessed for stroke severity and functional outcome,respectively. We found a significant difference in DD/Fg values between the three groups based on NIHSS scores at admission. Specifically, the DD/Fg values were higher in the poor functional outcome group (mRS score of 2-6) compared to the favorable functional outcome group (mRS score of 0-1) at the 1-year follow-up (P < 0.001). Additionally, the DD/Fg values were independently associated with poor functional prognosis at 1 year following the onset of stroke, even after adjusting for potential confounders (OR 9.21, 95% CI, 3.68–23.02, P<0.001). Our findings suggest that DD/Fg values at admission may serve as risk predictors for poor functional outcomes in patients with AIS 1 year after the stroke.