Background: The impact of coronavirus disease 2019 (COVID-19) related mental health status on chronic spontaneous urticaria (CSU) has not been addressed before. Objective: The aim of this study was to evaluate the depression, anxiety and stress levels, and the fear of COVID-19 in patients with mild-to-moderate CSU and to determine their impact on urticaria activity during the pandemic. Methods: A total of 509 patients with mild-to-moderate CSU were prospectively evaluated with validated scales, the Depression Anxiety Stress Scale 21 (DASS-21) and the Fear of COVID-19 Scale (FCV-19S) during the lockdown period (LP) and the return to normal period (RTNP). CSU activity was determined with the urticaria activity score summed over 7 days (UAS7) and medication scores (MS). UAS7 and MS before the pandemic were retrospectively collected from medical records. Results: The median UAS7 and MS were both significantly higher in the LP than in the median of related scores during the prepandemic period (p < 0.0001) and the RTNP (p < 0.0001). The mean FCV-19S and DASS-21 scores were both significantly higher in the LP than in the RTNP (p < 0.0001). The FCV-19S and the DASS-21 anxiety and stress subscales were significantly higher in women. The UAS7s were positively correlated with the FCV-19S and depression, anxiety, and stress subscale scores. Conclusion: Fear of COVID-19, anxiety, depression, and stress during the COVID-19 pandemic, especially when strict isolation measures are taken, have a significant impact on mental health and urticaria activity in patients with mild-to-moderate CSU, even though they are not infected. Psychological support for patients with CSU seems to be important to control disease activity during the pandemic.