Inhibitory interneurons are fundamental constituents of cortical circuits that process information to shape economic behaviors. However, the role of inhibitory interneurons in this process remains elusive at the core cortical reward-region, orbitofrontal cortex (OFC). Here, we show that presumed parvalbumin-containing GABAergic interneurons (fast-spiking neurons, FSNs) cooperate with presumed regular-spiking pyramidal neurons (RSNs) during economic-values computation. While monkeys perceived a visual lottery for probability and magnitude of rewards, identified FSNs occupied a small subset of OFC neurons (12%) with high-frequency firing-rates and wide dynamic-ranges, both are key intrinsic cellular characteristics to regulate cortical computation. We found that FSNs showed higher sensitivity to the probability and magnitude of rewards than RSNs. Unambiguously, both neural populations signaled expected values (i.e., probability times magnitude), but FSNs processed these reward's information strongly governed by the dynamic range. Thus, cooperative information processing between FSNs and RSNs provides a common cortical framework for computing economic values.