Abstract  Glial fibrillary acidic protein (GFAP)‐expressing cells (GFAP+ glial cells) are the predominant cell type in the central and peripheral nervous system (CNS and PNS). Our understanding of the role of GFAP+ glial cells and their signaling systems in vivo is limited due to our inability to manipulate these cells and their receptors in a cell‐type specific and non‐invasive manner. To circumvent this limitation, we developed a transgenic mouse line (GFAP‐hM3Dq mice) that expresses an engineered Gq protein‐coupled receptor (Gq‐GPCR) known as hM3Dq DREADD (Designer Receptor Exclusively Activated by Designer Drug) selectively in GFAP+ glial cells. The hM3Dq receptor is activated solely by a pharmacologically inert, but bioavailable, ligand (clozapine‐N‐oxide; CNO), while being non‐responsive to endogenous GPCR ligands. In GFAP‐hM3Dq mice, CNO administration increased heart rate, blood pressure and saliva formation, as well as decreased body temperature; parameters controlled by the autonomic nervous system (ANS). Additionally, changes in activity‐related behavior and motor coordination were observed following CNO administration. Genetically blocking IP3‐dependent Ca2+ increases in astrocytes failed to interfere with CNO‐mediated changes in ANS function, locomotor activity or motor coordination. Our findings reveal an unexpectedly broad role of GFAP+ glial cells in modulating complex physiology and behavior in vivo and suggest that these effects are not dependent on IP3‐dependent increases in astrocytic Ca2+. This article is protected by copyright. All rights reserved