Creatine consumption appears to have a positive impact on cognitive function in different populations but the effects of creatine in a young, healthy population are mixed. Additionally, exercise appears to benefit cognitive processes in young and older adults. The present study explored the ways in which exercise frequency may moderate the effect of creatine consumption on working memory, sustained attention, mind wandering, and speed of processing, in a young, healthy, adult population. Forty-two individuals were randomly assigned to a creatine condition (n = 20) or a control condition (n = 22). For each session, participants completed the Symmetry Span Task, Sustained Attention to Response Task with thought probes, the Pattern Comparison Task, Daily Inventory of Stressful Events, Perceived Stress Scale, State Trait Anxiety Inventory, and supplied a saliva sample. Participants in the creatine supplementation condition were instructed to consume 5g of creatine monohydrate per day for a 6-week period between sessions. Results suggested that exercise frequency was related to differences in working memory task performance. Exercise frequency moderated the effect of creatine consumption on sustained attention and mind wandering, such that beneficial effects were observed only among participants who consumed creatine and reported less frequent exercise. Results from this study suggest that creatine supplementation can serve as a possible aid to cognitive functioning in individuals who lead a sedentary lifestyle.