The victory, completed in four minutes under two hours, was built on the Dane's resilience, consistency and greater variation on the key points, and put the 27-year-old into her second final in the eight-woman event after losing in 2010.
Wozniacki goes on to meet the winner of the second semi-final between Venus Williams and Caroline Garcia later on Saturday, while Pliskova is left to rue a defeat that prevents her from being able to replace Simona Halep as world number one.
"We have had a lot of close matches this year and I was hoping today was my turn. It feels great to be in the final and I have been playing some great tennis this week," Wozniacki said in a courtside interview.
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Both players had raced out of the blocks in their previous three matches in Singapore but perhaps mindful of what was at stake, they made a cagey start to their semi-final, unable to stamp any sort of authority on proceedings.
Pliskova was the aggressor and found more success when she committed to her attacking shots, while Wozniacki was content to use her supreme court coverage and stonewall defence to stay in touch.
The first five games went with serve until the Czech edged ahead by instigating a run of four straight breaks of serve as Wozniacki staved off three set points in the 10th game stay alive in the set and eventually forced a tiebreak.
The Dane then raced into a 6-1 lead over the sleepwalking Pliskova before the Czech rose from her slumber to first save all five set points and then fashion three more of her own, which Wozniacki somehow managed to survive.
Wozniacki continued to cover every inch of the court to set up another set point, her sixth, with more defensive brilliance, and the former number one sealed the opener 11-9 in the breaker when Pliskova found the net with a backhand.
The Dane was full of confidence and attempted to break free with an early break in the second set to move 3-1 ahead but Pliskova refused to buckle and stormed back by stepping in to take her shots early to get the contest back on serve.
Wozniacki changed tactics again, however, and opted to push the ball into the corners to force Pliskova into some vital errors as she struggled out of position and the Dane broke once more for a 5-3 lead.
This time there would be no way back for Pliskova as Wozniacki sent a backhand crosscourt winner past her stranded opponent to storm into the final.
"It was a little bit crazy, managing to come back from those set points and then not feeling so good about myself after being 6-1 up in the tiebreak. It was kind of a roller-coaster and I am just happy that I got the first set under my belt," Wozniacki added.
Venus Williams rallied from the disappointment of losing a tight first set to blast her way past Caroline Garcia 6-7(3) 6-2 6-3 and set up a WTA Finals title showdown against Caroline Wozniacki on Saturday.
The evergreen American has enjoyed a brilliant campaign, reaching two grand slam finals in 2017, and the 37-year-old American was able to call on all her experience to find a way to stifle her upset-minded opponent in an engrossing encounter.
In the first semi-final, Denmark's Wozniacki stood her ground in the face of some incredible early pressure before pinning down Karolina Pliskova with a 7-6(9) 6-3 victory that ensured Simona Halep will end the year as world number one.
Williams and Garcia took the court in a battle between two players possessing huge forehands and a tendency to attack their opponent's second serve, the contest starting out as slow burner that lacked fluency after they traded early breaks.
Williams appeared troubled by a hip injury and was trying to keep the points short while Garcia became tentative every time she had a chance to break free, especially when she fashioned her first set point that came and went at 5-4.
Garcia was rewarded for being more positive in the tiebreak as Williams' serve wavered and the Frenchwoman wrapped up the opener on her second set point when her opponent sent another groundstroke wide and long.
The American increased her intensity in the second set and took advantage of Garcia's passivity to storm 4-1 clear, with Williams breaking for a second time in the eighth game against a weary-looking opponent to level up the contest.
Garcia had won nine of her last 10 three-set matches but was struggling to grab any sort of foothold in Williams' service games and the American shifted up a gear to grab the only break she needed in the eighth game and served it out for the win.
"Garcia competed so well in the whole tournament," Williams said of an opponent who won back-to-back titles in China to sneak into the event as the last qualifier.
"Every time I thought I had her, she would play amazing shots... but it's never over until the fat lady sings and I'm not fat," joked Williams, who won the tournament in 2008.
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