The Wimbledon champion has a 3-4 record versus the 14th-ranked Petkovic, who won their last two contests more than three years ago.
"It's been a long time since we played each other," Kvitova said after the draw on Friday. "She's been in good form. I know a little bit how she's playing, and we're gonna talk about the tactics for tomorrow. I need really to focus on myself, not really on her."
Lucie Safarova will play Germany No. 1 Angelique Kerber in the second singles on the indoor hard court at O2 Arena on Saturday.
The Czechs won the Fed Cup in 2011 and '12, while Germany is seeking its first title since 1992.
"We are nervous, definitely," Petkovic said. "We're trying to transform it into good energy and into positive emotions.
"Petra's such a great player. She's probably a little more experienced but we had a great preparation week. I'm ready for everything."
Petkovic comes into the final having won in Bulgaria on Sunday for her third WTA title of the year.
"I came here with lot of positive emotions," she said.
Kerber beat Safarova in their only previous encounter, in 2012 in Paris.
In Sunday's reverse singles, Kvitova first plays Kerber, then Safarova takes on Petkovic. In the final-closing doubles, the Czech pair of Andrea Hlavackova and Lucie Hradecka is set to play Julia Goerges and Sabine Lisicki.
"It's our best doubles team," Czech captain Petr Pala said. "If it gets to 2-2, that's the best team I can have."
The Germans have received a video message from Steffi Graf, who won the Fed Cup in 1992 with Germany captain Barbara Rittner.
The Czechs are expecting their own prominent supporter, Martina Navratilova, in the stands.