Background: Independent associations between screen time (ST)/physical activity (PA) and overweight (OW)/obesity have been demonstrated but little research exists on the role of ST among sufficiently active children. Purpose: To examine the combined influence of ST and PA on risk of OW/obesity in a nationally representative sample of 9-year-old Irish children. Methods: The sample in this cross sectional analysis contained 8568 children. Self-report parent data were used to group children into ST and PA categories and related to OW/obesity using forced entry logistic regression. Results: High ST (> 3 hours/day), bedroom TV and mobile phone ownership increased risk of OW/obesity in high and low active children (P < .05). Low PA (<9 bouts fortnightly) was also associated with OW/obesity. In combined analyses, OW/obesity was lowest in the reference low ST/high PA group with ORs of 1.38, 1.63, and 2.07, respectively, in the low ST/low PA, high ST/high PA, and high ST/low PA groups. Access to electronic media, low socioeconomic status, parental obesity, and not engaging in sports were all related to high ST (P < .05). Conclusion: This study supports findings that ST is associated with OW/Obesity demonstrating this separately in high and low active children.