The top seed will now play 21st seed Zvonareva who ended Pironkova's fairytale run
Defending champion Serena Williams reached her third successive Wimbledon final after seeing off a challenge from the gritty unseeded Czech Petra Kvitova 7-6(5), 6-2 on Thursday.
In the final, the top seed will play Russian 21st seed Vera Zvonareva who fought back from a set down to beat unseeded Bulgarian Tsvetana Pironkova 3-6, 6-3, 6-2 in the other semfinal.
The World No.1 was given a stiff challenge by the unseeded World No.62, but Kvitova began to run out of steam in the second set.
The American top seed's victory means that at least one of the Williams sisters has advanced to 10 out of 11 straight finals here, with Serena now having made six.
“It definitely wasn't easy. I worked really hard,” Williams said. “I'm happy to still be here, it's such a blessing to still be in the tournament.”
On Saturday's final, she said: “Vera is a great player. I've had some unbelievable matches against her.
“It will be tough. I feel like I have nothing to lose going into the final and she doesn't either, so it will be good.”
Since turning professional 10 years ago, Zvonareva has been dogged by doubts about her temperament as she has failed to fulfil her undoubted potential. She was perceived as a choker who would crumble at the most important moments.
Growing in confidence
Injuries have also blighted her career, but the 25-year-old has become a more confident, mature player in the last year and had already served notice of her improved mindset by reaching the Australian Open semifinals 18 months ago.
Pironkova's expectations were so low heading into Wimbledon that she only arranged for accommodation for the first week of the tournament.
The 22-year-old's apartment booking ran out before the semifinal so the Bulgarian embassy had to find her emergency accommodation.
Pironkova went for her shots right from the start and made enough of them to break for a 4-2 lead when a fortunate net cord went in her favour.
She had no trouble closing out the first set and looked well on top at that stage.
In the sixth game of the second set, Pironkova faltered on serve and the Russian went for the kill, breaking with a perfectly-placed volley.
She easily held serve to take the set and level the match. It was the first set Pironkova had dropped at the Championships this year.
Zvonareva was able to take full advantage as she broke in the first game of the final set when the Bulgarian sent a forehand long.
When Zvonareva held serve moments later, she had won six of the last seven games and the momentum would remain with her for the rest of the match.
Zvonareva broke again when Pironkova missed a forehand and then saved two break points before serving out the most important win of her life.
“I haven't quite realised what I've done yet,” Zvonareva said.
“It is very exciting. It's one of my dreams to be in the final.
“It was very tough out there, she's a young player but a very, very tough opponent.
“She started so well and I'm happy with the way I was able to hang in the match and turn it around.”