Kierstyn is of Irish origin, derived from the ancient Gaelic name Ciara, which means "dark" or "black." It is believed to have been inspired by the dark color of the heroine in an old Irish tale. The spelling Kierstyn is a modern variant, offering a unique twist on the classic Ciara.
The name Kierstyn experienced significant popularity in the late 1980s and early to mid-1990s, with a peak of 135 births recorded in 2007. However, its usage has steadily declined since then, reaching an all-time low of just 6 births in 2023.