Top-seeded Dimitrov beat Kyle Edmund 6-3, 6-7 (3), 6-4 in the quarterfinals on Friday to set up a meeting with No. 3-seeded Nick Kyrgios, who rebounded for a 1-6, 6-3, 6-4 win over former finalist Alexandr Dolgopolov.
Kyrgios wrapped up the first set in 37 minutes despite having to save five break points along the way.
The Aussie then full control of the match after Harrison dropped serve at the start of the second with a double fault.
As for the final, Kyrgios said he'd worked himself into the tournament and was ready to win a title with little more than a week to go before the Australian Open, the first major of the season.
The local favourite will now lock horns with American Ryan Harrison in the final on Sunday.
Australian Nick Kyrgios will be going for glory on home soil after reaching the final of the Brisbane International.
"I know that he's a unsafe opponent. I felt right at home", Kyrgios told the crowd afterwards.
Browns make notable personnel hires in Eliot Wolf and Alonzo Highsmith official
Since 2012, he had held the title of senior personnel executive after spending 13 years in the team's college scouting department. The Browns finished the regular season without a victory and are now 1-31 in the last two seasons under head coach Hue Jackson.
"He played a pretty solid first set, I played a pretty loose game to get broken", Kyrgios said.
Asked if he thought Tomic would be having any regrets about brushing Brisbane after two Australians made the semis, Kyrgios said: "It was obviously odd not seeing him playing any of these events".
In the opening set, things went with serve until the seventh game when the third-seeded Australian broke to lead 4-3 and went on to claim the opener 6-4.
"He was probably expected to win today, I thought", Kyrgios said of De Minaur's third straight victory in Brisbane after the teenager had previously notched just one ATP main draw victory in his career.
The victory elevated him from 21 to 17 on the world rankings, but Kyrgios will not commit to maintaining his more measured demeanour in the Australian Open.
Dimitrov, who survived two match points to beat local hope John Millman in the previous round, needed a solitary break to close out the match.
During the deciding third set, Kyrgios - already a break up - made a decision to take his chance by charging up on a Dimitrov serve.