Background: Physical inactivity and excess adiposity are thought to be detrimental to physical and cognitive health. However, implications of these interrelated health factors are rarely examined together; consequently, little is known regarding the concomitant contribution of physical activity and adiposity to cognition. Methods: Bivariate correlations and hierarchical linear regressions were conducted among a sample of adults between 25 and 45 years (N = 65). Attentional inhibition was assessed using an Eriksen Flanker task. Whole-body percent body fat (%Fat) was assessed using dual-energy X-ray absorptiometry. Daily percent time spent in moderate to vigorous physical activity (%MVPA) was monitored using an accelerometer (7 d). Results: After adjusting for significant covariates, %MVPA was a positive predictor of accuracy in the incongruent task (β = 0.31, P = .03). Individuals who engaged in greater %MVPA exhibited superior attentional inhibition. Additionally, there was an interaction effect of %Fat and %MVPA on attentional inhibition (β = 0.45, P = .04). Conclusion: The positive influence of MVPA on cognitive control persists following the adjustment of significant covariates and adiposity. Additionally, interactive effects between %Fat and %MVPA suggest that individuals with lower activity and greater adiposity exhibited poorer attentional inhibition. These findings have relevance for public health given the elevated rates of physical inactivity and obesity.