MaryKate started playing Field Hockey her freshman year of high school where she became the freshmen team's GK. Her first season was very good. Her team won most of their games and shut out some of the best schools in the state.

Her sophomore year she was placed on the varsity and jv team. This is because, throughout the season, she was competing with a junior GK to see who would play the semi-finals and finals. MaryKate only had three goals scored on her all season and her team has a 7-1-0 record. MaryKate was the only GK to shut out Cherry Creek High School, the highest-scoring team in the state. She was picked to be the semi-final and finals GK. During Semi-Finals her team won 3-1 against #1 seed Colorado Academy and during finals her team won. MaryKate Berg was awarded the Defensive MVP award and was an honorable mention for All-Conference.

Her junior year, MaryKate played as the starting GK for her Regis Jesuit's varsity team. Her team had an amazing season, they were undefeated with a 14-0-1 record. This includes shutting out Colorado Academy -the highest-scoring team in Colorado- during league and the state championship. MaryKate only let in 5 goals during the league games and none during playoffs. She was ranked #4 in the nation for her .2 GAA. MaryKate's team was the 5A state champions for their 2nd year in a row. MaryKate received the "Perfect Season" Award from her coach and was selected for the All-Conference and All-State First Team.

MaryKate played her first indoor season with Aurora Field Hockey. She played at the Colorado Winter Indoor Tournament 2020.

MaryKate was then a part of Club Lewy for the first half of 2021.

MaryKate guest played with Denver Field Hockey Club for the U19 Regional Club Championship. MaryKate was able to block many goals and showcase her sliding, diving, and hand skills and was awarded the Hot Wheels Player from the DFHC coach. She also played with them at Midwest Madness.

MaryKate guest played with East Coast Academy Field Hockey Club at 2021 Summer Escape. MaryKate also attended the GK Showcase available at the tournament.

Mid-July, MaryKate attended the Apex Summer Showcase. During this showcase, she got GK specific training from college coaches. At the end of the showcase, She was selected to be a part of the All-Star Team out of fourteen other GKs attending the showcase.

MaryKate then changed clubs to be a part of the Denver Field Hockey Club.

End of November, she attended the USA National Field Hockey Festival with DFHC.

MaryKate has also done a lot of training in camps. She has done private goalkeeper lessons with Paul Lewis and currently does lessons with Lisa Griffith. She also attended Futures 2020 camp, Winter Intermediate Indoor Camp 2020, Winter Advanced Indoor Camp 2020, Denver Field Hockey Fall Camp 2020, Denver Field Hockey Spring Camp 2021, and Nexus 2021. She was selected for Regional Nexus Camp but was unable to attend due to financial reasons.