Objectives This cross-sectional study assessed the prevalence of self-reported noncompliance with mandatory seatbelt-use law and examined the factors associated with noncompliance with seatbelt-use while driving in adult working population in Kuwait. Methods During October 2017, 822 adults aged 21–60 years from 11 government ministries and departments were enrolled in this study. Data were collected using a pre-tested, structured, and self-administered questionnaire. We computed the prevalence of self-reported noncompliance with mandatory seatbelt-use law while driving and evaluated the factors associated with noncompliance with seatbelt-use law while driving using a multivariable log-binomial regression model. The adjusted prevalence ratios (PR) and corresponding 95% confidence intervals (CI) were computed using model’s parameters’ estimates. Results Of 822 participants, 64.4% were females, 56.6% were 21 to 30 years old, 86.5% were Kuwaitis, and 70.3% had college and/or university level education. The prevalence of self-reported noncompliance with mandatory seatbelt-use law while driving was 55.5%, whereas the prevalence of noncompliance with self-reported mandatory use seatbelt as a passenger was 80.9%. Multivariable log-binomial regression model showed that after adjusting for the influence of other variables in the model, participants were more likely to be noncompliers with mandatory seatbelt law while driving, if they believed that seatbelt does not protect against injuries during road traffic crashes (RTC) (adjusted PR = 1.20; 95% CI: 1.06–1.37; p = 0.004) or if they were ever fined for not wearing seatbelt (adjusted PR = 1.34; 95% CI: 1.24–1.47; p <  0.001). Furthermore, participants were significantly more likely to be noncompliers with mandatory seatbelt law while driving, if they were unaware of implemented mandatory seatbelt law in Kuwait (adjusted PR = 1.11; 95% CI: 1.04–1.19; p = 0.003). Conclusions The prevalence of noncompliance with mandatory seatbelt-use law in the adult working population of Kuwait is considerably high. Being unaware of mandatory seatbelt use law, belief that seatbelt does not protect during RTC, and having ever been fined in the past for not having seatbelt on while driving were significant predictors of noncompliance with seatbelt-use law. These results warrant the focused mass education and rigorous enforcement of seatbelt-use law while driving. These strategies are likely to enhance the adherence to seatbelt-use law and minimize RTCs related injuries and mortality among adult drivers in this and other similar settings in the region. If implemented, future studies may look at the impact of such interventions on RTCs related frequency and severity of injuries in this and other similar settings.