Background To investigate changes in mental health outcomes among racial groups between 2019 and 2020. Methods A retrospective cohort study was conducted using the third through fourth quarters of 2019-2020 longitudinal data from the National Health Interview Survey. Self-reports of diagnosed depression and anxiety disorder were key outcomes. We calculated the percentage of depression and anxiety disorder across baseline sample characteristics. Discrete-time hazard models stratified by race/ethnicity were conducted, with hazard ratios (HRs), 95% confidence intervals (CIs), and p-values reported. Results Of a total 10,415 individuals, 16.3 and 14.1% reported that they were diagnosed with depression and anxiety disorder in 2019, respectively. In the multivariable model, only Asian-Americans experienced a significant increase in the probability of receiving a diagnosis of depression by 104% between 2019 and 2020 (HR 2.04, 95%CI 1.19-3.52; p = 0.010). Also, Asian-Americans had a 97% (HR 1.97, 95%CI 1.23-3.15; p = 0.005) greater probability of being diagnosed with anxiety disorder in 2020 than in the previous year, while Hispanics and Whites had a relatively moderate increase of 40% (HR 1.40, 95%CI 1.01-1.76; p = 0.040) and 11% (HR 1.11, 95%CI 1.03-1.20; p = 0.007), respectively. Conclusions Asian-Americans experienced a disproportionate increase in mental health conditions during the COVID-19 pandemic. Discriminatory behaviors against Asian-Americans may be important contributors. The study findings suggest the need for serious actions to address this issue.