Associations between daily physical activity (PA) and executive functioning have rarely been investigated among young adults. This study examined these associations among 162 university students (74 females and 88 males; mean age = 19.0, SD = 1.1 years). We measured PA objectively, using hip-mounted accelerometers, and assessed executive functioning in a task-switching paradigm. Anthropometrics measurements were gathered using standardized procedures. Through linear regression modeling, we found moderate-to-vigorous physical activity (β = −0.19, 95% CI = [−0.35, −0.03], p = .02) and light physical activity (β = −0.17, 95% CI = [−0.34, −0.01], p = .04) to be associated with smaller global reaction time switch costs. Total PA was not associated with task-switching performance, and there were no statistically significant associations between PA indicators and local switch costs. As both moderate-to-vigorous and light physical activities were associated with better executive function in young adults, there can be important cognitive benefits to remaining physically active.