McKenna Marvin was born on March 4, 2004 in Texas to Mike and Michelle Marvin. She has a brother, Matthew and three dogs named Kiwi, Chief and Rocky. Currently, McKenna is a student at Prestonwood Christian Academy (PCAPlus) and she will graduate from high school in 2022. During McKenna's spare time, she enjoys painting, cooking, snowboarding and hanging out wth her family and friends.

McKenna began gymnastics after attending a birthday party at a gym. She has always been active, strong and loved to flip. She taught herself to do flips on the trampoline at the birthday party! She asked to take a gymnastics class, so her parents put her in recreational classes once a week when she was five years old. Two years later, her parents found a gym closer to their home and they invited her to be on the team. McKenna began her first competition season when she was seven years old as a level 3 gymnast and never looked back.

As a level 7 gymnast in 2015, McKenna scored a 37.775 in the all-around and placed first on balance beam with a 9.850 at the State Championships. She qualified to the Region 3 Championships where she finished third in the all-around with a 37.950 and third on uneven bars. She was named to America's Top 100 on balance beam twice. McKenna moved up to level 8 for the 2016 season. She placed fourth on floor exercise with a 9.700 at the State Championships and fourth on floor exercise with a 9.550 at the Region 3 Championships.

In 2017 as a first-year level 9 gymnast, McKenna finished second in the all-around with a 37.800 and first on balance beam and floor exercise at the State Championships. At the Region 3 Championships, she placed fourth in the all-around with a 37.275, second on floor exercise and fourth on uneven bars. McKenna qualified to the Level 9 Western Nationals in Boise, ID where she placed fifth in the all-around with a 37.300, first on uneven bars and fourth on floor exercise. McKenna was named to America's Top 100 on floor exercise twice. McKenna continued competing level 9 for the 2018 season where she placed second in the all-around with a 37.625, first on floor exercise and second on uneven bars at the State Championships. At the Region 3 Championships, she finished third on floor exercise and seventh on vault. She qualified to the Level 9 Western Nationals in Salt City Lake, UT, finishing 13th overall, seventh on uneven bars and ninth on floor exercise.

McKenna moved up to level 10 for the 2019 season where she earned a bronze medal on floor exercise at the State Championships. In 2020, McKenna qualified to the Level 10 State Championships but was unable to compete due to COVID-19 pandemic.

McKenna trains about 30 hours per week at Zenith Elite Gymnastics in McKinney, TX under coaches Simona Iuga-Rytzell and Tammy De Guzman. McKenna is working hard to become a successful level 10 gymnast. Her long-term goal is to obtain a Division I college gymnastics scholarship.