She then kept Vekic under pressure throughout, saving two break points on her own serve, before breaking for the second time in the set to win the match 6-3 and a meeting with Osaka.
Playing in her first tournament since upsetting Serena Williams to win the U.S. Open on September 8, third-seeded Osaka hadn't dropped a set previous to Sunday's final but was frustrated from the outset by the big-serving Czech player.
"My serve is my biggest weapon and it was key today", she added.
"It was another long one today", Pliskova said after the match. "I haven't really had much time to rest, so I feel exhausted right now".
Not since Victoria Azarenka in 2012 has a player won their first tournament after a maiden Grand Slam triumph, but Osaka has been playing some excellent tennis and will surely receive the vocal backing of her home crowd.
The second set continued in the same direction with both servers on top until Pliskova pounced in game nine, breaking her opponent to love and giving her the chance to serve out for the title. "I haven't really had much time to rest, so I feel exhausted right now".
In Pliskova's 6-2, 4-6, 6-3 victory against Donna Vekic in the last four she becomes the fifth player of this season to register 40 main draw match wins.
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 unsafe forehand.
In WTA tournaments elsewhere, Kiki Bertens defeated Ajla Tomljanovic 7-6 (7/2), 4-6, 6-2 in the final of the Korea Open in Seoul. "I'm just happy that I also have a title as a married woman". I was expecting a tough one. "That's sort of like me playing ahead, but I'm still not 100 percent sure yet". That's normal in semi-finals - there are no easy opponents.
After saving two match points against American qualifier Alison Riske in the last round, and coming back from a set down against Daria Gavrilova earlier in the tournament, Pliskova had to go the distance once again, needing 2 hours and 5 minutes.