Yarrow grows in mildly disturbed grasslands, meadows, roadsides and open woods across the temperate Northern Hemisphere. In North America both native and introduced Eurasian populations exist, which makes its status complicated; VASCAN records it from every Canadian province and territory including Quebec. Its flowers support native bees and other beneficial insects, and its leaves feed moth larvae.
The genus is named for Achilles, who according to legend carried the plant with his army to treat battle wounds, and millefolium is Latin for thousand-leaved, a reference to the finely divided foliage. Human use of yarrow is very old, with evidence reaching back to Neanderthal burial sites about 60,000 years ago.