McKenna was a very active toddler, so her parents decided to enroll her into gymnastics so she could have a safe place to burn off energy. She trained at Active Athletics in Littleton, Colorado for levels 5-9. She was the 2012 Level 5 State All-Around and Balance Beam Champion. In 2014, McKenna skipped level 6 and quickly moved up to level 7 where she placed eighth in the all-around with a 37.675 and fourth on balance beam. She competed level 8 for the next two seasons. She qualified to the 2015 Region 3 Championships. In 2016, McKenna won the vault title at the State Championships. At the Region 3 Championships, she placed seventh on vault, eighth on uneven bars and 12th in the all-around with a 37.000.

Following her 2017 season, McKenna moved to Colorado Gymnastics Institute in Aurora, CO. She had a great level 9 season in 2018 where she placed second in the all-around with a 37.700, first on vault and second on floor exercise at the State Championships. At the Region 3 Championships, she finished third in the all-around with a 37.375 and first on vault. McKenna qualified to the Level 9 Western Nationals in Salt Lake City, UT, finishing seventh in the all-around with a 37.425, second on vault and eighth on uneven bars.

As a first-year level 10 gymnast in 2019, McKenna finished second on balance beam, third on vault and uneven bars and fourth in the all-around at the State Championships. She qualified to the Region 3 Championships, finishing eighth on floor exercise. In 2020, McKenna had a great season where she qualified to Nastia Liukin Supergirl Cup! She scored. 37.525 in the junior division. She also qualified to the State Championships but was unable to compete due to COVID-19 pandemic. In 2021, McKenna grabbed gold medals on balance beam, floor exercise and in the all-around at the State Championships. She qualified to the Junior Olympic Nationals after finishing fourth in the all-around and third on floor exercise at the Region 3 Championships. At the Nationals in Daytona Beach, FL, McKenna placed 12th on floor exercise out of 56 gymnasts.

In 2022, McKenna won vault, floor exercise and all-around titles at the Level 10 State Championships. At the Region 3 Championships, she finished second in the all-around with a 38.125, first on floor exercise and second on vault. She qualified to the Level 10 National Championships in Mesa, AZ.