The 13-time Grand Slam champion advanced to her seventh Wimbledon final by beating second-seeded Victoria Azarenka of Belarus 6-3, 7-6 (6) Thursday.
Williams finished with a Wimbledon record 24 aces, and won 20 of the 24 points on her serve in the first set.
Williams will face Agnieszka Radwanska in Saturday's final. The third-seeded Pole beat Angelique Kerber 6-3, 6-4 in the other semifinal.
In the men's semifinals, defending champion Novak Djokovic will face six-time winner Roger Federer on Friday, while Andy Murray will take on Jo-Wilfried Tsonga.