Ostapenko won as a wildcard in 2021, and the world number 14 confirmed her place in this year's showdown by overcoming Camila Giorgi.
She is the first female player to reach back-to-back finals in Eastbourne since Caroline Wozniacki in 2017 and 2018.
The Latvian, who is also going to compete for the doubles title, prevailed 6-2 6-2 and will now go up against Kvitova. The pair have faced off eight times previously, with each player winning four matches.
It is Kvitova's first appearance in a final in 2022, with the former world number two – and two-time Wimbledon champion – having ended Beatriz Haddad Maia's winning streak.
Haddad Maia won in Birmingham last week and Nottingham the week before, but her run came to an end at 12 matches, with Kvitova triumphing 7-6 (7-5) 6-4.
"For me, a final after almost a year [without one] will be great, so I’m glad already," said Kvitova, who was a runner-up at Eastbourne in 2011 and last reached a final on grass in Birmingham four years ago.
"Jelena loves to play here, obviously, we saw it, she has a really great game for grass."
Meanwhile, at the Bad Homburg Open, 2019 US Open champion Bianca Andreescu reached her sixth career final courtesy of a walkover against Simona Halep.
The Romanian withdrew from the semi-final clash with a neck injury, which will worry the 2019 Wimbledon champion ahead of the season's third grand slam at the All England Club.
"I am sorry that I had to withdraw today before my semi-final match," Halep said in a statement.
"But unfortunately I woke up this morning with a blocked neck and this is not allowing me to perform to the best of my ability."
Andreescu will face Caroline Garcia, who saved a match point before going on to beat fellow Frenchwoman Alize Cornet 7-6 (11-9) 3-6 7-5 to reach an 11th tour-level showpiece.