It set up a fascinating final with the Crusaders at Hamilton on Saturday.
But it was a close-run thing as the ACT Brumbies powered up defensively to almost de-fang the home pack for all but the last 70 minutes of the game.
Three mistakes proved costly for the Brumbies. Firstly they were penalised at a scrum, their only weak point on the night, and McKenzie landed his fourth penalty goal from 50 metres out with a wet ball.
The Brumbies kicked the restart out on the full. Then, when the ball was kicked long to the Brumbies fullback Tom Wright, he tried to run at the defence, was held up, and the turnover went to the Chiefs.
The Chiefs pulled a set move with replacement halfback Cortez Ratima running around on the blindside as a support runner. The Brumbies kicked again, but replacement first five-eighths Josh Ioane took the ball, charged ahead 10 metres, and with McKenzie moving up to first receiver, the chance was on.
McKenzie ran into a huge gap and passed wide to Shaun Stevenson, who had moved to the left wing. Stevenson threw a pass infield, and McKenzie took it as the play moved towards the goalposts. Lock Brodie Retallick, who had a massive game in the tight, picked up the ball, dived over to score, and put the issue beyond doubt.
It wholly contrasted with the high-scoring and dominating first semifinal won by the Crusaders in Christchurch. Heavy rain at the outset in Hamilton had its effect, and there was an emphasis by both teams on probing with kicks for the best possible position.
In a first half dominated by the kicking approach from both sides, the Chiefs finally got deep into the Brumbies' 22m area with a powerful scrum on Brumbies' ball to rock the visitors. The Chiefs couldn't buy any luck for the final 10 minutes of the half.
They tried two lineout drives, a tap penalty and two scrum attempts to create a scoring foundation, but each time, they were countered; their last chance was three minutes into injury time, but No8 Luke Jacobson, who had an outstanding defensive half, had the ball knocked from his grasp by desperate Brumbies defence.
The second half was more of the same. The Brumbies headed into the final quarter by getting deep into the Chief's 22m area and looked to launch their dangerous rolling maul. Still, the stout Chiefs defence, courtesy of replacement No8 Pita Gus Sowakula, brought the reward when he contested the ball on the ground to give the Chiefs vital impetus.
They inched their way downfield from that base to set up the final and, as it proved, a winning chance.
The Brumbies were formidable in testing the defensive skills of the Chiefs. But the home team was firm, missing only nine tackles compared to 34 by the Brumbies, who were forced to make 206 tackles compared to 146 by the Chiefs.
Loose forwards Rob Valetini and Pete Samu were outstanding in a competitive battle with Jacobson and home skipper and flanker Sam Cane at the breakdown. Centre Len Ikitau was powerful in backline defence.
Chiefs 19 (Brodie Retallick try; Damian McKenzie con, 4 pen) Brumbies 6 (Noah Lolesio 2 pen). HT: 6-3
DHL Super Rugby Pacific Final confirmed:
Chiefs v Crusaders, Saturday 24 June, 7.05pm NZT, FMG Stadium Waikato.