Selective visual attention is a key feature of adaptive behavior, improving stimulus detection and response speed. Although it is well established that several measures of neural activity are modulated by attention in many brain areas, it is unclear whether and how these changes in activity correlate with behavior and how different cell types contribute to these mechanisms. To unravel the link between the behavioral benefits induced by spatial attention and its neuronal mechanisms, we analyzed neuronal responses obtained from simultaneous extracellular recordings in PFC and visual area V4 of two macaques engaged in a color-cued covert attention task. When attention was directed inside a neuron’s receptive field (RF), spiking activity was negatively correlated with response time on a trial-by-trial basis, while with attention outside the RF, significant positive correlations (particularly prominent in V4) were found, indicating that both the selective enhancement of the target representation and the suppression of distractors are linked to faster responses. In PFC, firing rates carried more information about the target location in fast response trials and earlier compared to V4. Ιncorrect responses were associated with diminished attentional effects in both areas. Interestingly, whereas in PFC, activity of mainly broad spiking putative excitatory neurons contributed to the neuronal effects associated with improved behavior, in V4, narrow spiking putative inhibitory interneurons contributed the larger effects, revealing distinct cell-type dependent contributions in the two areas. Acknowledgments: Supported by the European Union’s Horizon 2020 under the Marie Skłodowska-Curie grant and Innovative Training Network: In2PrimateBrain (GA 956669).