We investigated whether the presence of explicit instantaneous positive feedback in video games might facilitate intrinsic motivation for and performance on a subsequent unrelated cognitive task. We hypothesized that the experience of flow, which would be facilitated by the instantaneous positive feedback during gaming, would facilitate positive motivational spillover on the subsequent cognitive task. We used an experimental design manipulating the instantaneous positive feedback during the game (n = 77 and n = 86 college students for the control and the experimental groups, respectively) and estimated a structural equation model. Controlling gender, prior gaming experience, and trait intrinsic motivation, the average level of flow for the participants who received instantaneous positive feedback was significantly higher than the others. Flow, in turn, positively and significantly predicted the performance and state intrinsic motivation for the cognitive task. Our findings pointed to a motivational spillover process initiated by the affective experience during video gaming.