<p>This study was planned to determine how stress, physical activity, and daily step count predict cognitive flexibility. Studies used socio-demographic forms, the Cognitive Flexibility Inventory (CFI), the Perceived Stress Scale (PSS), and the International Physical Activity Questionnaire (IPAQ). The study also recorded participants’ 1-week average step count. The study had 88 participants, with an average age of 20.72 ± 2.10 years. In the study, a moderate negative correlation was determined between the CFI total score and the PSS total score (<i>r</i> = − 0.596, <i>p</i> = 0.000), and a moderate positive correlation was determined between the daily step count (DSC) (<i>r</i> = 0.539, <i>p</i> = 0.001). It was determined that there was a moderate statistical relationship between the CFI total score and IPAQ (<i>r</i> = 0.559; <i>p</i> = 0.001). It was observed that the contribution of physical activity, step count, and PSS variables to the model created to explain the variation in the CFI score was statistically significant (<i>p</i> = 0.019, <i>p</i> = 0.004, and <i>p</i> = 0.000, respectively). The perceived stress variable, whose standardized regression coefficient was − 0.392, was observed to have the highest contribution to the model. The three independent variables included in the model explain 33.9% of the change in CFI score. In conclusion, it was determined that while the perceived stress level decreased, and physical activity and the number of daily steps increased, the level of cognitive flexibility increased.</p>