This study investigates the changes in prevalence estimates, severity, and risk factors of anxiety among healthcare workers (HCWs) over the first year of the COVID-19 pandemic. A survey was distributed among HCWs using snowball sampling, collecting their socio-demographics, occupation, and anxiety symptoms as measured by the Generalized Anxiety Disorder-7 (GAD-7) scale. It was distributed one month after the pandemic’s onset in Jordan between 15 and 30 April 2020 (onset group) and after one year between 15 and 30 March 2021 (one-year group). A total of 422 HCWs were included (211 in each group). The one-year group reported a higher risk of GAD (30.8% vs. 16.6%; p = 0.001), a higher mean (SD) GAD-7 score (7.94 (5.29) vs. 6.15 (4.15); p < 0.001), and more severe symptoms (p = 0.003). Univariate analyses showed that participants who were younger, women, unmarried, had lower monthly incomes, underwent testing for COVID-19, had higher contact with COVID-19 patients, did not receive special education, and were unsatisfied with the institutional COVID-19 preparedness scored higher on the GAD-7 scale and had more severe symptoms than their counterparts in both groups. Unlike the onset group, occupation as a physician, COVID-19 infection history, and perception of remarkable changes in work were associated with higher anxiety scores and severity among the one-year group. The COVID-19 vaccine was a relative protective action. Logistic regression analyses showed that the female gender was a risk factor for developing GAD at the pandemic onset, while poor satisfaction with institutional preparedness was a significant GAD risk factor in the one-year group. Low monthly income and lack of special education were the shared risk factors for GAD in both groups. This study reveals a significant rise in anxiety among HCWs over a year of the COVID-19 pandemic and shows the vulnerable sub-groups who likely need psychological interventions.