Mackenzie holds a Bachelor of Arts in Political Science from StFX University. She graduated with First Class Honours in May 2020 and was the recipient of the Jules Léger Scholarship for Achievement in the Social Sciences, the Walter Kontak Prize in Political Science and the Dr. John B. Stewart Scholarship for Political Science. Previously, Mackenzie attended Ashbury College in Ottawa, where she was a member of the varsity basketball and rugby, and junior and senior volleyball teams, and was always engaged in student life. Although she is not from Nova Scotia, Mackenzie went to StFX on the recommendation of her grandfather, who graduated from StFX in 1948, over 70 years earlier than she did.

While at StFX, Mackenzie was a teaching assistant for the Department of Economics and a research assistant for Dr. Lavinia Stan of the Department of Political Science. During her university summers, Mackenzie built on her understanding of politics and economics by completing an internship at the United States Embassy in Ottawa and a research internship at the Brian Mulroney Institute of Government at StFX. Over many previous summers, Mackenzie worked as a camp counsellor, lifeguard and swim instructor at Camp Oconto in Tichborne, Ontario. She was also a competitive alpine ski coach in western Quebec during the winter seasons. As an athlete herself, Mackenzie trained and raced with a competitive alpine ski team in Canada and the United States for eight years before coaching. More recently, some of her favourite volunteer endeavours have been being a member of the Shinerama National Leadership Team with Cystic Fibrosis Canada, a swim coach with Special Olympics Nova Scotia and a Chapter Vice-President with Best Buddies Canada. In her free time, Mackenzie enjoys alpine skiing, swimming, biking and spending time with her friends and family.