Katlyn is of Irish origin, derived from the name Catherine, which means 'pure' in Greek. It gained popularity in the United States during the late 20th century, peaking in the mid-1990s before experiencing a steady decline. Notable individuals named Katlyn include American singer-songwriter Katlyn Carlson and Canadian figure skater Katlyn Osmond.
Katlyn saw its peak in popularity during 1989 with five babies named that year.