Kim Seong-yeon is a South Korean voice actor who began her career in 2007 as a member of the 5th class at Daekyo Broadcasting. The following year, in 2008, she joined Daewon Broadcasting as part of its 1st class before transitioning to a freelance career in 2010.

Recognized for a mature and warm vocal quality, her repertoire is versatile, encompassing a wide array of character types. She is frequently cast in roles such as older sisters, mothers, and young boys, but has also demonstrated a capacity for lively and cool characters, as well as intense dual-personality performances.

Kim Seong-yeon has contributed her voice to a significant number of animated series. In the magical girl genre, she is known for voicing Milk in Yes! Precure 5 GoGo!, a character who also appears in human form as Kurumi Mimino / Milky Rose. She also voiced Ami Mizuno / Sailor Mercury in the re-dubbed version of the Sailor Moon series. In the series Psychic Squad, she took on the roles of both Chisato Hanai and Hotaru Nowaki.

Her other notable anime voice roles include Angelina Durless (Madame Red) in Black Butler, Angel / Sorano Aguria in Fairy Tail, Nanami Takahashi in We Were There, and Hitomiko in Inuyasha The Final Act. She has also appeared in various re-dubbed versions of long-running detective series such as Detective Conan and The Kindaichi Case Files.

Beyond anime, her work spans other media. She has voiced characters in special effects series, including roles across the Kamen Rider, Super Sentai, and Precure franchises. Her work in video games includes voicing Reika in the Spirit Hunter series and Tiana in MapleStory.