Objectives: The aim of this cross-sectional study was to examine the differences between participants’ socio-demographic variables, and the Depression, Anxiety, and Stress Scale [DASS] and its three sub-scales (depression, anxiety, and stress) among individuals who lived in Kuwait during the total lockdown due to the COVID-19 pandemic. Method: An online survey was distributed to 975 participants via WhatsApp and Twitter, using the convenience non-random sampling method. The survey consisted of three sections: a written consent form, demographic items, and the DASS. Results: The findings showed that Kuwaitis, males, widowed, individuals who were 50 and above, businessmen, higher educational level had a greater likelihood of experiencing depression, anxiety, and stress than the other groups during this pandemic. Conclusion: It was determined that intervention programs aimed at improving the population’s mental health are needed in the lockdown period to support mental health and wellbeing and reduce mental illness symptoms during the COVID-19 pandemic.