Background: Temporal changes in the prevalence of anxiety disorders/symptoms for patients with cancer at the end of life (EOL) remain unclear. This study was undertaken to describe changes in the prevalence of severe anxiety symptoms and to identify its correlates in the last year of life for patients with cancer. Methods: A convenience sample of 325 patients with cancer was followed until death. Severe anxiety symptoms were identified as anxiety subscale scores of 11 or greater on the Hospital Anxiety and Depression Scale. Longitudinal changes in and correlates of severe anxiety symptoms were examined from demographics, disease-related characteristics, disease burden, perceived burden to others, and social support using multivariate logistic regression modeling with generalized estimating equations. Results: The prevalence of severe anxiety symptoms increased as death approached (18.6%, 21.9%, 26.7%, and 33.4% at 181–365, 91–180, 31–90, and 1–30 days before death, respectively). However, after controlling for covariates, this temporal increase was not significant. The prevalence of severe anxiety symptoms was not associated with fixed demographics and disease-related characteristics, except for diagnosis and metastatic status, but was significantly higher in patients with cancer with high physical symptom distress, severe depressive symptoms, high perceived burden to others, and strong perceived social support. Conclusions: Severe anxiety symptoms were not associated with time proximity to death per se but were related to factors modifiable by high-quality EOL care. Clinicians may decrease the likelihood of severe anxiety symptoms at EOL by adequately managing physical and depressive symptoms and lightening perceived burden to others for patients strongly connected with their social network to improve their psychological well-being.