Kiera is of Irish origin, meaning 'dark-haired'. It's a feminine form of the Irish name Ciaráin, which means 'little dark one'. The name gained popularity in English-speaking countries during the late 20th century, often used as an alternative to traditional names like Kira or Kierra.
"The name Kiera peaked in popularity with 8 babies named in 1989, then declined to 6 in 1990 and further down to 5 in 1993, bringing the total number of newborns named Kiera over this period to 19."