Hyun-Ji Kim is a South Korean voice actor who began her career in 2006 as part of the sixth cohort of the CJ ENM Voice Actor Society, working exclusively with the company until 2009 before transitioning to freelance work. She is recognized for a clear and refreshing vocal tone, which has allowed her to portray a wide spectrum of characters, from lively and cute girls to mature women, boys, and even animal roles.

She has become a prominent voice in Korean-dubbed anime and animation, taking on numerous leading roles. Among her most notable performances is Serena in the Pokémon animated series, a role she has voiced across multiple films including Pokémon the Movie: Diancie and the Cocoon of Destruction, Pokémon the Movie: Hoopa and the Clash of Ages, and Pokémon the Movie: Volcanion and the Mechanical Marvel. Her association with the Pokémon franchise also includes voicing the character Belle in the Black & White series and returning to the role of Serena for Pokémon Journeys: The Series. Beyond Pokémon, her extensive anime and animation credits include Azusa Nakano in K-On!, Wendy Marvell in Fairy Tail, Pinkie Pie in My Little Pony, and the main character Lala in PriPara. She has also taken on boy roles, such as Kangsan in Beyblade Burst.

Kim Hyun-Ji's voice is also widely recognized in the video game industry. One of her most famous roles is D.Va (Song Ha-na) in the global hit Overwatch. In a notable casting story, she was reportedly discovered for this role after a radio appearance where she had been drinking, and Blizzard Entertainment felt her voice was a perfect match for the character. She has also lent her voice to major games such as Genshin Impact as Eula, Cookie Run: Witch's Castle as Cheerful Cookie, and Honkai: Star Rail as Asta. Her other game credits include Rue in Elsword, Lily Bloomerchen in Soulworker, and Miri in Mabinogi Heroes.

Kim is known for her strong singing ability, often performing insert songs and theme songs for the characters she plays. This skill is particularly showcased in her role as Pinkie Pie and in various "idol" anime series like PriPara and Dream Jewel Prism Stone, where she sang numerous songs for her characters and others. A native of Busan, she is also proficient in the Busan dialect, which she has utilized for character localization, such as for the character Serena in Dream Jewel Prism Stone. She has frequently collaborated with other voice actors from her cohort, including Kim Hyun-shim.