And that she did all the way to the end, stopping the clock at 11m 20s, smashing the old record.
The time placed her 16th out of the 621 firefighters in the prestigious division. A total of 1000 firefighters competed and raised more than $1.3 million from the event.
Mckenzie said the hardest part of the race was between the 36th and 44th floors and the burn in the legs kicked in.
Another factor was taking into consideration the dizziness caused by the multiple righthand turns going up the stairwell.
"It was a bit disorienting."
Knowing what to expect during the race and also gaining international experience by competing in the Seattle firefighter stairclimb (69 flights of stairs, 1356 steps) in March helped Mckenzie crack the record.
But she reckons there's room for improvement.
"Now it's about technique and learning how to turn the corners faster."
So don't be surprised if she breaks her own record next year.
But what gave her extra motivation was her cousin in Auckland City Hospital getting treatment for leukaemia.
"My cousin has been going through some intense treatment after being diagnosed at Christmas. That gave me plenty of mental motivation and the best part was going to see him on Sunday to show him my medal."
Mckenzie said her training meant climbing Mount Lion, Mount Manaia and Parihaka numerous times. But her secret was filling up a weed spraying unit with water to add weight to her climb then tipping it out at the top so she could run back down.
No concession was made for footwear and her heavy work boots were pulled on for training runs.
She said there was a real buzz at the event with volunteer firefighters raising so much money for Leukaemia and Blood Cancer New Zealand.
Northland brigades and money raised:
Kamo - $12,707
Ngunguru - $11,288
Ruakākā - $9116
Marsden - $22 8,619
Kaikohe Rural Fire Force - $8364
Paihia - $6823
Dargaville - $6676
Onerahi - $5557
Kerikeri - $5533
Kaikohe - $5220
Mangawhai - $4223
Ahipara - $3923