Background Identifying factors associated with delayed diagnosis of cerebral venous thrombosis (CVT) can inform future strategies for early detection. Methods and Results We conducted a retrospective cohort study including all participants from ACTION-CVT (Anticoagulation in the Treatment of Cerebral Venous Thrombosis) study who had dates of neurologic symptom onset and CVT diagnosis available. Delayed diagnosis was defined as CVT diagnosis occurring in the fourth (final) quartile of days from symptom onset. The primary study outcome was modified Rankin Scale score of ≤1 at 90 days; secondary outcomes included partial/complete CVT recanalization on last available imaging and modified Rankin Scale score of ≤2. Logistic regression analyses were used to identify independent variables associated with delayed diagnosis and to assess the association of delayed diagnosis and outcomes. A total of 935 patients were included in our study. Median time from symptom onset to diagnosis was 4 days (interquartile range, 1-10 days). Delayed CVT diagnosis (time to diagnosis >10 days) occurred in 212 patients (23%). Isolated headache (adjusted odds ratio [aOR], 2.36 [95% CI, 1.50-3.73]; <0.001), older age (aOR by 1 year, 1.02 [95% CI, 1.004-1.03]; =0.01), and papilledema (aOR, 2.00 [95% CI, 1.03-3.89]; =0.04) were associated with diagnostic delay, whereas higher National Institutes of Health Stroke Scale score was inversely associated with diagnostic delay (aOR by 1 point, 0.95 [95% CI, 0.89-1.00]; =0.049). Delayed diagnosis was not associated with modified Rankin Scale score of ≤1 at 90 days (aOR, 1.08 [95% CI, 0.60-1.96]; =0.79). Conclusions In a large multicenter cohort, a quarter of included patients with CVT were diagnosed >10 days after symptom onset. Delayed CVT diagnosis was associated with the symptom of isolated headache and was not associated with adverse clinical outcomes.