- Stage Names: Hyoyeon (효연), DJ HYO, HYO
- Birth Name: Kim Hyoyeon (김효연)
- Nicknames: Princess Fiona, Dancing Queen
- Birthdate: September 22, 1989
- Birthplace: Incheon, South Korea
- Blood Type: AB
- Height: 160cm
- Weight: 49kg
- Religion: Christian
- Languages: Chinese (Fluent), Japanese (Basic), English (Basic)
- Education: Chungbuk Middle School
- Hobbies: Shopping, Movies
- Relationship: Kim Joon Hyung (Writer) (2012–2014)
Kim is most known for her popping, waving, and Hip-hop dancing techniques that she learned from the Winners Dance School while she was a trainee. Prior to her debut, she traveled to Beijing, China in 2004 with Super Junior’s Siwon to learn Mandarin and more about Chinese culture.
- [2016.08.26] Born To Be Wild (Park Jin Young, Hyoyeon, Min, Jo Kwon)
- [2016.12.02] Mystery
- [2017.06.01] Wannabe
- [2018.04.18] Sober (HYO)
- [2018.11.13] Punk Right Now (HYO)
- [2019.02.23] Punk Right Now (Remixes) (HYO)
- [2019.07.20] Badster (HYO)
- [2020.07.22] DESSERT (Feat. Loopy, SOYEON ((G)I-DLE)) (HYO)
- [2020.10.30] Think About Me (Raiden, HYO)
- [2016.06.28] Taeyeon - Why (#5 Up & Down (feat. Hyoyeon))
- [2020.06.05] GOOD GIRL Episode 1 (#4 TURL (Hyoyeon, Cheetah))
- [2020.06.19] GOOD GIRL Episode 3 (#1 WITCH (Manyeosanyang) (Yeeun, Jiwoo, Jamie, Cheetah, Hyoyeon))
- [2020.06.26] GOOD GIRL Episode 4 (#4 GG (Ailee, Jiwoo, Hyoyeon))
- [2020.07.03] GOOD GIRL FINAL (#5 I Do What I Want (Hyoyeon, Lee Young Ji))
-  Oh! My Lady (cameo)
- She was a trainee with SM Entertainment for six years and one month.
- She was BoA's silhouette dancer in her "Over the Top" performance at the 2005 M.net Asian Music Awards.
- She became an SM Entertainment trainee when she was twelve years old in 2000 by being discovered at an SM Entertainment casting system.
- She learned Jazz dance, Latin dance, and a variety of other styles when she was in elementary school. She didn't become interested in Hip-hop dance until she entered junior high school.
- Her favorite foods are soup and Korean food.
- Her favorite fashion is feminine shoes with baggy pants
- Her motto is "Everyone that works hard will succeed".