Karly Kim was born on April 28, 2003 in Michigan to Walt and Heather Kim. She has a younger brother, Cooper who is also a gymnast at Gedderts' Twistars. Currently, Karly is an honor student at Grand Ledge High School and she will graduate from high school in 2021. When she has time outside of gymnastics, she enjoys singing, playing piano, choreographing floor routines, camping and fishing.

Karly began tumbling classes in 2005 at Gedderts' Twistars USA when she was two years old. Her mother, Heather Kim, is a former collegiate gymnast at Michigan State University and coached at Gedderts' Twistars USA. Karly started competing level 4 in 2011 where she placed third in the all-around at the State Championships. At the 2012 Level 5 State Championships, she finished sixth in the all-around with a 37.225.

In 2013 as a level 6 gymnast, Karly placed fourth in the all-around and fourth on uneven bars at the State Championships. She moved up to level 7 for the 2014 season where she placed sixth in the all-around and second on vault and floor exercise. Karly was named to America's Top 100 on balance beam in level 7. Karly competed as a level 8 gymnast for the next two seasons. In 2015, she finished second in the all-around with a 38.175 and first on floor exercise at the State Championships. She qualified to the Region 5 Championships, finishing fifth in the all-around with a 37.500. Karly was named to 2015 America's Top 100 on uneven bars, balance beam and floor exercise for level 8. In 2016, Karly finished third in the all-around and first on floor exercise at the State Championships. At the Region 5 Championships, she placed third in the all-around with a 37.825 and third on vault and floor exercise.

Karly moved up to level 9 for the 2017 season. She had a great meet at the State Championships where she placed fourth in the all-around with a 37.000, first on floor exercise and second on uneven bars. At the Region 5 Championships, she finished fourth in the all-around with a 37.400 and first on floor exercise. This qualified Karly to the Level 9 Eastern Nationals in Lansing, MI where she placed eighth in the all-around with a 37.300 and second on uneven bars and floor exercise. Karly was named to America's Top 100 for floor exercise in level 9. In 2018, Karly finished third in the all-around with a 37.375 and third on floor exercise at the State Championships. At the Region 5 Championships, she placed fourth in the all-around with 37.350, first on vault and second on floor exercise. She qualified to the Level 9 Eastern Nationals in Rochester, NY, finishing fourth on balance beam and fifth on floor exercise. In 2019, Karly had a great season where she won balance beam and all-around titles at the State Championships (37.125) and Region 5 Championships (37.750). She qualified to the Level 9 Eastern Nationals in Kissimmee, FL, finishing second in the all-around with a 37.700, second on floor exercise and fifth on balance beam.

Karly trains 23-25 hours per week at Gedderts' Twistars in Lansing, MI under coach Brett Wargo. Karly is working hard to become a successful level 10 gymnast and to obtain a college gymnastics scholarship.