A rapid review of previous outbreaks shows that a quarantine policy had greater effects on one’s psychological state including post-traumatic stress disorder (PTSD), confusion and anger caused by various stressors. This study aimed to assess the levels of Post-Traumatic Stress Disorder (PTSD) and its associations with suicidal behavior among Malaysian adults following Movement Control Order (MCO) during the COVID-19 pandemic in Malaysia. This cross-sectional study was distributed using an online standardized questionnaire composed of three parts, the socio-demographic characteristics, PTSD assessment using PTSD Checklist for DSM-5 and the suicidal behavior assessment using Suicidal Behaviors Questionnaire-Revised (SBQ-R). Almost half of the respondents had high PTSD symptoms (41.7 %) and low PTSD was 58.3 % among Malaysian adults. Furthermore, 69.6 % of participants had no suicidal behavior but, 30.4 % from the participants has suicidal behavior. This study found single status with highest PTSD (83.3 %) and marital status had significant correlation with PTSD which p-value was < 0.05. Malay was high percentage in high PTSD (74.6 %) and significant correlation between race and PTSD (p < 0.05). Employment status also had significant correlation with PTSD with p-value was 0.002 and students was counted highest PTSD (65.7 %). This study identified some socio-demographic factors and suicidal behavior associated with PTSD among Malaysian adults, which may lay ground for further interventions.