The mechanically activated non-selective cation channel Piezo1 is a determinant of vascular architecture during early development. Piezo1-deficient embryos die at midgestation with disorganized blood vessels. However, the role of stretch-activated ion channels (SACs) in arterial smooth muscle cells in the adult remains unknown. Here, we show that Piezo1 is highly expressed in myocytes of small-diameter arteries and that smooth-muscle-specific Piezo1 deletion fully impairs SAC activity. While Piezo1 is dispensable for the arterial myogenic tone, it is involved in the structural remodeling of small arteries. Increased Piezo1 opening has a trophic effect on resistance arteries, influencing both diameter and wall thickness in hypertension. Piezo1 mediates a rise in cytosolic calcium and stimulates activity of transglutaminases, cross-linking enzymes required for the remodeling of small arteries. In conclusion, we have established the connection between an early mechanosensitive process, involving Piezo1 in smooth muscle cells, and a clinically relevant arterial remodeling.