<p>Perceiving a lack of control over one’s environment can impair cognitive performance and may reduce willingness to invest cognitive effort. Across two experiments (<i>N</i> = 624), we tested whether experimentally induced uncontrollability decreases subsequent effort-based choice and whether monetary rewards offset this effect. Uncontrollability was induced using Behavioral Helplessness Training, and effort-based choice was assessed in a Voluntary Task Switching paradigm in which participants could choose between repeating a task or switching to an alternative. The Voluntary Switch Rate served as the primary behavioral index of choosing the option treated as more cognitively demanding, that is, as requiring greater cognitive control. We used a shape/location variant in Experiment 1 and a letter/number variant in Experiment 2 with double registration and 20% invalid trials to better match task difficulty, separate choice from execution, and induce a degree of environmental unpredictability. Rewards robustly increased switching in both experiments. In Experiment 1, low control attenuated sensitivity to rewards. In Experiment 2, uncontrollability reduced switching overall and increased the reward magnitude required to justify switching. Exploratory mediation analyses further suggested that reduced motivation and increased negative affect mediated the link between uncontrollability and switching behavior. Overall, these results advance our understanding of motivational processes underlying helplessness and provide implications for the design of interventions aimed at sustaining cognitive engagement under uncontrollable conditions.</p>