The response of the insular cortex (IC) and amygdala to stimuli of positive and negative valence were found to be altered in patients with anxiety disorders. However, the coding properties of neurons controlling anxiety and valence remain unknown. Combining photometry recordings and chemogenetics in mice, we uncover the anxiogenic control of projection neurons in the anterior IC (aIC), independently of their projection target. Using viral tracing and ex vivo electrophysiology, we characterize the monosynaptic aIC to the basolateral amygdala (BLA) connection, and employed projection-specific optogenetics, to reveal anxiogenic properties of aIC-BLA neurons in anxiety-related behaviors. Finally, using photometry recordings, we identified that aIC-BLA neurons are active in anxiogenic spaces, and in response to aversive stimuli. Together, these findings show that negative valence, as well as anxiety-related information and behaviors, are encoded by aICBLA glutamatergic neurons, providing a starting point to understand how alterations of this pathway contribute to psychiatric disorders.