Astroglial networks mediated by gap junction channels contribute to neurotransmission and promote neuronal coordination. Connexin 30, one of the two main astroglial gap junction forming protein, alters at the behavioral level the reactivity of mice to novel environment and at the synaptic level excitatory transmission. However, the role and function of Cx30 at the neuronal network level remain unclear. We thus investigated whether Cx30 regulates neuronal population bursts and associated convulsive behavior. We found in vivo that Cx30 is upregulated by kainate-induced seizures and that it regulates in turn the severity of associated behavioral seizures. Using electrophysiology ex vivo, we report that Cx30 regulates aberrant network activity via control of astroglial glutamate clearance independently of gap-junction mediated biochemical coupling. Altogether, our results indicate that astroglial Cx30 is an important player in orchestrating neuronal network activity.