<p>Developmental Coordination Disorder (DCD) is a prevalent condition that persistently affects motor skills performance from childhood through adulthood. Because the term DCD requires a formal clinical diagnosis, the terms at risk for DCD (r-DCD) and probable DCD (pDCD) were used in this study to acknowledge that participants may present characteristics consistent with the disorder. However, few studies have examined DCD traits in two developmental periods (childhood and adulthood) as a primary predictor of physical activity and sedentary behaviour in adulthood, while accounting for sociodemographic and health-related factors. To this end, we investigated whether longitudinal DCD traits are associated with physical activity and sedentary behaviour in university students, controlling for sociodemographic and health-related variables. Additionally, we tested the severity of DCD in the relationship with physical activity and sedentary behaviour in a sensitivity analysis considering pDCD over developmental periods. A total of 124 participants (mean age: 25.48 ± 7.20) completed the Adult DCD Checklist (ADC), the short-form of the International Physical Activity Questionnaire (IPAQ-short), and a structured questionnaire. Logistic regression analyses were conducted to examine associations between variables, adjusting for sex and age (Model 1), sociodemographic variables (Model 2), and health-related variables (Model 3). DCD traits significantly increased the odds of insufficient physical activity and elevated sedentary behaviour across all developmental periods, with some variations in Models 2 and 3 for physical activity. However, the association with sedentary behaviour persisted across developmental periods, and became stronger after a sensitivity analysis using pDCD, with odds ratios ranging from 3.99 to 11.99 in Model 1, and from 3.47 to 11.35 in Models 2 and 3. This study highlights the potential impact of DCD on reducing levels of physical activity and increasing sedentary behaviour in adults.</p>