Sensing blood, Pliskova broke for 5-4 and, moments later, delivered the coup de grace with a sixth ace Osaka barely wafted her racket at.
Pliskova soon set her foot after unleashing another brutal drive as Osaka made flat-fault into the net.
Osaka and Pliskova will face off Sunday for the third time overall and second this year with a Premier-level title on the line.
"It was important for me to play two sets and not go three sets - also for recovery for the next tournament - and I needed a match like this", Pliskova, fourth seed, said after the win. "I have played Pliskova twice already and so I know she is a great player", said Osaka, who won their last meeting at Indian Wells. But I served really well and that got me out of a lot of trouble today.
In her postgame press conference, Pliskova said she had been wary of Osaka's power and had tailored a game plan aimed at neutralizing the U.S. Open champion's risky forehand.
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Pliskova, meanwhile, was more than happy to take advantage of Osaka's sloppiness, converting both her break point opportunities and reeling off the last 11 points to secure a second WTA title of the campaign.
"The chances of me playing in the next tournament are very low", she said. "She was missing quite a lot today so it was working, so I didn't change anything".
Former World No 1 Karolina Pliskova won the title by snapping the 20-year-old's 10-match winning streak to triumph, 6-4, 6-4 and win her 11th career title.
"I've literally never felt more exhausted in my entire life, so I kind of want to say the chances of me playing in the next tournament are very low", she said. "I haven't really had much time to rest, so I feel exhausted right now". "She has basically every shot and a really good serve, so I know it's going to be a really hard match". "Naomi was maybe a little bit exhausted, you could see that".
She can still, however, take heart from her recent run of form as she looks to finish the year on a strong note.
The Wuhan Open, which began on Sunday and ends on September 29, still boasts a strong field despite Osaka's withdrawal, with the top five women's players, including world number one Simona Halep, all taking part.