World number five Nishikori had an almost identical win against Swiss U.S. Open champion Stan Wawrinka, who went down 7-6(3) 6-3 in the first semi-final of the warmup event for this month's Australian Open.
There was little to separate Dimitrov and 2016 Wimbledon finalist Raonic in the first set, both players making the most of their big serves and not offering a single break-point opportunity.
Dimitrov managed to nose ahead by edging the first set tiebreak 9-7 before racing away in the second with two breaks of serve to seal the match.
"I couldn't imagine a better scenario for sure," Dimitrov said in a court-side interview. "I have lot of respect for him and it's always a pleasure playing against him.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
"Right now I am just focussed on my performance. In previous matches I wasn't returning as well. Against Milos, the only chance you have is to get into a rally against him."
Dimitrov has never won against his opponent in Sunday's final with Nishikori enjoying a 3-0 head-to-head record.
"Nishikori is one of the trickiest players out there," Dimitrov added. "He has a tremendous fighting spirit and has improved his game quite a bit.
"He has quite a few weapons if you think about it. It's not going to be an easy match for sure. But I am focussed on myself and what I need to improve and what I need to get better for Melbourne."
Nishikori, the 2014 U.S. Open finalist, won five of the final six points in the tiebreaker to claim the first set. After an early exchange of breaks in the second, the Rio Olympic bronze medallist got the decisive break in the seventh game.
"I'm feeling very happy to be in the final tomorrow. I've tried many times and this is the first time to get to Sunday in Brisbane," the 27-year-old said.
"Especially beating Stan today, it's been a good start to the year.
"Dimi started playing much better last year, especially at the end of the season. He's going to be a tough opponent."
(Reporting by Sudipto Ganguly in Mumbai; Editing by John O'Brien)
