Kvitova pumped her fist and danced with team mates after outlasting the 10th-ranked German 7-6 4-6 6-4 in a fluctuating three-hour match.
“I am just glad I did it,” Kvitova, who added to her haul of three WTA titles in 2014 including a second Wimbledon crown, said from courtside.
“It was really up and down from the beginning of the match. It was a big fight for every single point.”
The win gave the Czech team an unbeatable 3-0 lead over Germany who were making their first final appearance since Steffi Graf led them to the 1992 title.
The Czechs have now won the Fed Cup eight times, including five as Czechoslovakia. Only the United States have won more, with 17 in total, the last coming in 2000.
Martina Navratilova, who won the event with the 1975 Czechoslovak team, was among the capacity 13,000 crowd at the O2 Arena in Prague, where the nation last hoisted the Fed Cup trophy in 2012, the second of back-to-back championships.
Kvitova and team mate Lucie Safarova swept to straight-set wins in the opening matches on Saturday, putting the German side – led by Kerber and Andrea Petkovic – in a tight spot.
Hard-hitting Czech left-hander Kvitova proved too much.
“I gave everything I had today and, in the end, Petra was better,” Kerber said.
“It was two or three points that decided the match and it went down to her. She deserved to win but I think we both played at a high level today.”
The German looked close to narrowing the Czechs’ lead but she failed to capitalize on crucial points in the rollercoaster 76 minute opener that set the tone for the day.
Both players controlled their serves to start but then Kvitova struggled with errors and found herself down 5-2. The German, though, failed to convert her first set point after Kvitova smashed a backhand cross-court winner and then broke Kerber to level at 5-5.
Kerber went up again but missed on five set points as another Kvitova cross-court backhand forced a tiebreak in which the Czech surged ahead and used a tricky drop shot to give her two set point chances with which she wasted little time.
Kvitova took that momentum to storm ahead 3-0 in the second set before Kerber calmed down and won the next four games, stayed in control and won the set when Kvitova hit a backhand wide, one of her 62 errors, more than twice as many as Kerber.
In the third set, Kerber again blazed ahead to 4-1 lead before Kvitova dug herself out and lifted the home supporters to their feet for good when Kerber sent a backhand into the net on the Czech’s fourth match point.
“It was a rollercoaster,” Czech team captain Petr Pala said. “It was an extraordinary match. It had everything that you expect from a match like this.” -Reuters