Flexible decision making is vital for survival. Animals must continuously evaluate their environment, making choices to maximize future gains. To facilitate decision making, multiple brain regions represent values of choice options and update them based on environmental interactions, connecting past experiences with future plans. Yet, the neural mechanisms generating these representations remain unclear. Here, we hypothesize that the claustrum, a subcortical nucleus highly interconnected with the neocortex, encodes decision variables and aids in sustaining their representations in cerebral cortex. In a dynamic foraging task, where mice chose between reward options with fluctuating probabilities, we recorded neural activity in the anterior claustrum. Remarkably, we found that approximately 50\% of claustrum neurons exhibited long-lasting, stable changes in firing rate that encoded total action values. Additionally, the claustrum contained a greater proportion of neurons encoding total value compared to the medial prefrontal cortex (mPFC). These findings, together with ongoing work, aim to clarify the claustrum’s role in dynamic decision making and offer insights into how decision variables are maintained in cortical networks during flexible behavior.