<p>Adaptive decision-making under risk requires individuals to flexibly adjust their risk-taking behavior after losses. Such post-loss risk adjustment is shaped by self-control (SC) and achievement motivation (AM), yet whether and how these two traits interact to influence this adjustment remains unknown, as well as its underlying neural correlates. To address this question, we recruited two independent samples (discovery: N₁ = 425; replication: N₂ = 182) to ask them undergo the resting-state fMRI scanning, finish the psychological measurements, and Balloon Analogue Risk Task (BART) used to measure post-loss risk adjustment (K_loss). The behavior results showed a significant interaction effect between SC and AM: higher SC predicted greater post-loss risk reduction (lower K_loss), but only among individuals with low AM, indicating that achievement motivation moderates how self-control shapes adaptive reactions to loss. At the neural level, converging voxel-based morphometry and rsFC results revealed an interaction effect between SC and AM in the left putamen along with functional connectivity (FC) between the left putamen and the anterior cingulate cortex (ACC). Moreover, a moderated mediation analysis demonstrated that the left putamen–ACC FC mediated the relationship between SC and K_loss exclusively in low-AM individuals. These effects replicated in the independent sample, underscoring the robustness of the behavior results and the identified function pathway. Collectively, these findings highlight a putamen–ACC circuit through which self-control and achievement motivation jointly influence adaptive post-loss risk adjustment. The results provide novel evidence that SC and AM shape risk-taking behavior through through mechanisms associated with monitoring and processing of conflict signals.</p>