The Czech tennis star suffered damage to the tendons and nerves of her left, playing hand and underwent nearly four hours of surgery.
"I was attacked in my apartment by an individual with a knife. In my attempt to defend myself, I was badly injured on my left hand," she said on her Facebook page
before her lengthy operation.
"I am shaken, but fortunate to be alive. The injury is severe and I will need to see specialists, but if you know anything about me I am strong and I will fight this."
Czech police told CNN that the attack took place just before 8.30 a.m. CET in Kvitova's apartment near the center of Prostejov, a small city about 160 miles east of Prague where a number of Czech tennis pros live and train during the offseason.
"The attacker was a man aged around 35 years, his identity is unknown and he is on the run. Police are working to determine what happened," the police spokesperson said.
Karel Tejkal, the spokesman for the former world No. 2, told the state-run Czech Radio that "it looks like it was a random act and not a planned action."
The injuries were severe enough that Kvitova, who won Wimbledon in 2011 and 2014, was tended to by an emergency ambulance.
"We received a call this morning about an injured 26-year-old woman who suffered injuries to her hand," a medical emergency spokesman in Prostejov said.
Later, Kvitova's three hour, 45-minute operation went "very well" considering "the extent of the damage," said her PR manager Katie Spellman.
"Doctors repaired damage to tendons in all five digits of the left hand as well as two nerves," Spellman said in an email to CNN.
Kvitova, added Spellman, must wear a cast for six to eight weeks and won't be able to put any weight on the hand for three months.
One of the top players in the women's game, Kvitova hours before the attack announced her withdrawal from January's Hopman Cup tournament in Australia due to a stress fracture in her foot.
Kvitova was quick to reassure her fans, also posting a statement on the Facebook page of Czech Federation Cup team a few hours after Tuesday's incident.
She received numerous messages of support on Twitter from the likes of Martina Navratilova, Billie Jean King, Caroline Wozniacki, Garbine Muguruza and Ana Ivanovic.
"Thank you for all the messages and support. What happened to me was certainly not pleasant, but it's over. Now it's (time for) doctors to (attend to) my hand," wrote Kvitova, who was part of the Czech team which last month won the international event for the third year in a row.
"I trust them and I hope it turns out well, I have the best care and I am in touch with (my) loved ones.
"The worst is behind me. Thank you once again ... do not worry about me!"
Kvitova's agent declined CNN's request to interview her for this story.
It isn't the first time a highly ranked tennis player has been attacked at home. In 2007, former world No. 5 Anna Chakvetadze was robbed by six armed men in her hometown of Moscow.
The Russian was tied up and threatened with a knife, while her parents were beaten.
The thieves ran off with over $300,000 worth of items, including a luxury watch the then-20-year-old had just been given at a tournament, according to the New York Times.
Though she claimed to have put the incident behind her, Chakvetadze was never again the same player. After suffered numerous physical setbacks, she retired in 2013 at age 26.
More famously, former world No. 1 Monica Seles was stabbed -- but that happened during a match. During a changeover in 1993, Gunter Parche, an obsessed fan of her rival Steffi Graf, stabbed Seles in the back.
Although Seles physically recovered in a few weeks, she took two years off from the game to recover mentally and never regained top form.
Seles -- who at the point of her attack had won eight grand slams -- came back to win one more at the 1996 Australian Open.
Although she did not reach another major final, Seles kept playing until 2003.