COVID-19 has a negative effect on the psychological well-being of psychiatric nurses. Thus, examining the psychosocial response of nurses is important for preventing more serious mental health problems and disruption of the quality of nursing care. This study aimed to evaluate the psychosocial problems of nurses who provided nursing care to patients with mental health disorders during the COVID-19 pandemic. A quantitative study with a cross-sectional design was conducted. The 101 nurses at Central Mental Health Hospital who provide nursing care to patients with mental health disorders were recruited through consecutive sampling. The instruments used were the demographic questionnaire, the Expanded Nursing Stress Scale, Zung Self-Rating Anxiety Scale, and The Connor–Davidson Resilience Scale 25. Univariate and bivariate analyses were used to process the data. The mean score of 45.1 (±24.3) was obtained for the ENSS; around 97% of nurses have a work stress score below the average, 4.95% have mild-moderate anxiety, and 28.7% have a low level of resilience. Work stress and contact frequency, work stress and gender, anxiety and contact frequency, as well as resilience and contact frequency all correlated significantly (
p
value <0.05). The Pearson test showed a significant positive correlation between work stress and anxiety (
p
: 0.002, r: 0.299). However, there was no significant correlation between anxiety and resilience (
p
: 0.643, r: 0.47), nor between work stress and resilience (
p
: 0.643; r: 0.47). Psychosocial disorders that psychiatric nurses face include occupational stress, mild-moderate anxiety, and low resilience. The government can create specific infection control guidelines for the mental health setting, and hospital management or ward leaders can also provide support to psychiatric nurses to increase resilience in reducing psychosocial problems.