Gap junctions (GJs) play a pivotal role in intercellular communication between eukaryotic cells, including transfer of biomolecules that contribute to the innate and adaptive immune response. However, if, how and why viruses affect gap junction intercellular communication (GJIC) remains largely unexplored. Here, we describe how the alphaherpesvirus pseudorabies virus (PRV) triggers ERK1/2-mediated phosphorylation of the main gap junction component connexin 43 (Cx43) and closure of GJIC, which depends on the viral protein pUL46. Consequently, a UL46null PRV mutant is unable to phosphorylate Cx43 or inhibit GJIC and displays reduced intercellular spread, which is effectively rescued by pharmacological inhibition of GJIC. Intercellular spread of UL46null PRV is also rescued by inhibition of the stimulator of interferon genes (STING), suggesting that pUL46-mediated suppression of GJIC contributes to intercellular virus spread by hindering intercellular communication that activates STING. The current study identifies key viral and cellular proteins involved in alphaherpesvirus-mediated suppression of GJIC and reveals that GJIC inhibition enhances virus intercellular spread, thereby opening new avenues for the design of targeted antiviral therapies.