MacKenzie was born in 1992[2] and grew up in theWaihopai Valley. Her parents are Aiden and Alison MacKenzie, and she has a brother and a sister.[3] She attendedMarlborough Girls' College inBlenheim[4] and being from a remote farm, she hasn't lived at home since age 13, but has either lived in flats or for board.[5] She is and continues to be a member of the Wairau Rowing Club,[6] despite having moved toCambridge in 2012 to train at the national rowing centre.[5][3] MacKenzie isgluten-intolerant and for that reason, much of her food is homemade rather than bought. She promotes healthy food recipes through a website that she runs with her friend from school,Megan Craig, a squash champion.[5]
The 2016 rowing year did not start out that successful for Edward and MacKenzie, and at bothWorld Rowing Cups that New Zealand attended that year, they came third, beaten by different nations at those regattas.[13][14][15] When they competed at the2016 Summer Olympics inRio de Janeiro later that year, they came fourth in thelightweight double sculls,[16] which was disappointing to them.[13] The following month, MacKenzie announced that she "needed a break" for 12 months. She would keep herself fit, but do some other activities that she had been interested in for some time,[17] including commencing her yoga teacher training with her friend Megan Craig.[18] Her rowing partner for the last few years, Edward, would also take a year off.[19] Both also took the 2018 rowing season off, but neither has announced their retirement.[20]
In 2013, she was votedMarlborough Sportswoman of the Year. In 2014 and 2015, she won the supreme award Marlborough Sportsperson of the Year.[3] In 2016, she was again vote Marlborough Sportswoman of the Year, beaten to the supreme award by rally co-driverJohn Kennard.[21] MacKenzie and Edward were team nominees in theHalberg Awards in both 2014 and 2015, but on neither occasion did they become finalists.[22][23]