Objective: Anxiety is one of the most common complications in patients with stroke, but studies on its relationship to functional outcomes are limited and controversial. We investigated the association between post-stroke anxiety (PSA) and a 1-year trajectory of functional outcome. Methods: A total of 423 patients were recruited within 2 weeks after a stroke (acute phase) during hospitalization. Of them, 306 (72.3%) completed follow-up examinations 1 year thereafter (chronic phase). Anxiety was evaluated using the Hospital Anxiety and Depression Scale-Anxiety subscale, and functional outcomes were measured using the National Institutes of Health Stroke Scale for stroke severity, the Barthel Index for activities of daily living (ADL), and the Mini-Mental State Examination for cognitive function at 2 weeks and 1 year. A range of demographic and clinical covariates were considered. The cross-sectional and longitudinal associations between PSA and functional outcomes were investigated. Results: PSA at the acute phase was not associated with functional outcomes at the cross-sectional point, but predicted worsening of outcome on stroke severity and ADL 1 year after stroke. PSA at the chronic phase was cross-sectionally associated with poor functional outcomes in all three measures. All associations were independent of potential covariates. Conclusion: Screening for anxiety is recommended even during the acute phase of stroke, considering its independent detrimental effect on functional prognosis. Screening for anxiety during the chronic phase is also encouraged, as this may reflect the functional status of stroke.