McCormick was born and raised in Mount Gambier, South Australia, before moving to Adelaide in 2011 where she attended Walford Anglican School for Girls. She played junior football for Blue Lake SC in Mount Gambier along with Cricket and Australian rules Football at national level.
McCormick made her debut in the ALW for Adelaide United in December 2012. She grew up playing attacking midfield, but was transitioned into a defender by Adelaide in the 2013-14 W-League where she was awarded the club's Player of The Year. She was included in an Australian Schoolgirls team to tour South America in 2013, and was named player of the tournament.
Jenna joined Canberra United for 2 seasons 2015. In 2016, she moved to Iceland to play for Stjarnan in the Úrvalsdeild; making her debut as a substitute in a win over Selfoss. Jenna returned to Canberra United for the 2016-17 season.
In July 2017, McCormick signed to play the second half of the 2017 season with Medkila IL in the Toppserien, the top tier of women's soccer in Norway.
In September 2017, Jenna committed to return to Adelaide United for the 2017-18 ALW
In October 2018, McCormick signed to play for Brisbane Roar for the ALW 2018-19 season where she finished with being awarded the Defender of The Year award..
In April 2016, McCormick declared her interest in playing in the newly formed AFL Women's competition, the first professional women's Australian rules football league. She was drafted by Adelaide in the 2016 AFL Women's draft.
McCormick missed round 1 of the 2017 season to play for Canberra United in the W-League semi-final on 5 February 2017. She debuted in round 2 of the 2017 season against the Western Bulldogs, and played seven games including the Grand Final and went on to win the inaugural AFLW Premiership in 2017.
Adelaide signed McCormick for the 2018 season during the trade period in May 2017, and she again missed the opening round of the season due to ALW commitments, joining the team for their round 2 match against Melbourne.
McCormick signed on with the Crows for Season 3 of the AFLW where she played in 5 out of 7 games for the regular season. Jenna played in the team's Preliminary final defeating Geelong and went on to play in another Grand Final where the Adelaide Football Club went onto win their 2nd AFLW Premiership.
In 2019/20, Jenna played for Melbourne Victory in the ALW, helping them to a semi-finals appearance where they fell short to eventual champions Sydney FC.
McCormick was honoured with her Australian national team debut with the Matildas on November 9th 2019 where she started in a 2-1 international friendly victory vs Chile at Bankwest Stadium in front of 20,029 fans.
Jenna found herself in Spain, Sevilla in 2020 with Real Betis Balompié in the Primera División Feminina but mutually agreed to terminate her contract after 5 months and joined Melbourne City in Australia where she played her football in the 2020/21 ALW.
Jenna has just returned from Denmark after plying her trade with AGF Fodbold in Denmark's top women's division.
Returning back to Adelaide, she again joined her home club of Adelaide United for the 2022/2023. The season didn't quite end as planned finishing mid table.
So, a new season once again has come around, and Jenna has signed with one of her previous clubs Brisbane Roar. Jenna enjoyed one of her best seasons of her career at Brisbane and hopes to replicate that success in the 23/24 campaign.