Cognitive control, specifically inhibition, is required to adapt behavior in response to environmental changes. While reward expectancy is known to shape cognitive strategies, the autonomic mechanisms underlying these adaptations—such as changes in pupil size—remain poorly understood. This study hypothesized that reward cues influence behavioral strategies, with these adaptations reflected in autonomic responses measured via pupil size, a marker of cognitive effort. Twenty-seven participants performed a rewarded stop-signal task (SST) with three reward conditions: Go plus, Neutral, and Stop plus. In the Go plus condition, participants were informed that they would receive a greater reward if they performed the movement (Go trials) than when they inhibited it (Stop trials), and vice versa in the Stop plus condition. Finally, in the Neutral condition, the reward was the same for both the Go and Stop trials performed correctly. Behavioral data and pupil size were analyzed to determine how reward influenced task performance and cognitive effort. Our results indicate that participants strategically adjusted behavior their behavior to align with reward condition: they show longer reaction times in response to the Go trial in the Stop plus condition, where inhibitory success was most rewarded. Accuracy in Go trials was higher in Go plus and Neutral conditions, while inhibition ability did not show a difference across reward conditions. Pupillometry revealed greater pupil size in the Neutral condition than Go plus and Stop plus, suggesting greater cognitive effort. Our findings suggest that reward expectation shapes proactive cognitive strategies, with participants modulating motor control to maximize rewards. Pupil size data indicate greater cognitive effort is exerted when task strategies require balanced focus to achieve rewards in both trial types. These results provide valuable insights into the interplay between reward sensitivity and cognitive control, with potential applications in developing rehabilitation strategies for individuals with impaired inhibitory control.