Serena, bidding for a seventh Wimbledon and an Open Era record-equalling 22nd Grand Slam title, took just 48mins 34sec, the fastest ever semi-final at the All England Club, to secure a 6-2, 6-0 win over world number 50 Elena Vesnina.
But her hopes of meeting Venus for the fifth time in a Wimbledon final and ninth time at a major were shattered when fourth seed Angelique Kerber, the Australian Open champion, saw off the 36-year-old 6-4, 6-4.
Serena, playing in her 32nd Grand Slam semi-final, blasted last-four debutant Vesnina off the sun-kissed Centre Court in front of Prince William’s wife Kate watching from up in the Royal Box.
The American fired 11 aces, 28 winners and committed just seven unforced errors, breaking serve five times to reach her 28th Grand Slam final.
Vesnina won just three points off the Williams serve in the first set and none in the second.
“I’m very happy. I was really focused today. We’ve had tough matches before and I knew she could bring it to me on this surface,” said Williams, who has now defeated the Russian five times in five meetings.
Despite the painfully one-sided semi-final Williams, into her third Grand Slam final of the year, insisted it had been a tough workout.
“It’s never easy out there, every point you have to fight for,” she said.
Vesnina, who was due to face Serena again in the women’s doubles later Thursday, admitted she just wasn’t good enough.
“I felt like I had no chance. Serena was playing really good. She was in a great mood, and her serve was working really well. She was placing it amazingly,” said the Russian.
“She was just better all over the court.”
Thursday’s contest saw Serena race to a 4-0 lead in the first set before 29-year-old Vesnina got on the board. But the set was over in 28 minutes courtesy of Williams’s seventh ace.
The second set was wrapped up in just 20 minutes with breaks in the first, third and fifth games.
Saturday’s final will give Serena a chance to win a first major of the season after losing to Kerber in the final in Melbourne and Garbine Muguruza in Paris.
Kerber saw off five-time champion Venus in 71 minutes on Centre Court to reach her first All England Club title match.
“Venus won so many times here and was playing really well. That’s why I’m so happy to reach my first Wimbledon final,” Kerber said.
“It’s a really good feeling. I’m really enjoying my tennis life.”
Kerber, 28, stunned Serena to win her maiden Grand Slam crown in the Australian Open final in January.
Kerber can now set her sights on becoming the first player to defeat both of the American siblings in the same Grand Slam since Kim Clijsters at the 2009 US Open.
If she can cause another upset against Serena, Kerber would become the first German woman to win Wimbledon since Steffi Graf in 1996.
She has raced through her six matches at Wimbledon without dropping a set, has a WTA tour-best 34 match wins in 2016 and is guaranteed to rise to a career-high second in the world rankings next week.
Venus had won all eight of her previous Wimbledon semi-finals dating back 16 years to her maiden appearance in the last four when she defeated Serena.
But in her first All England Club semi-final for seven years, Venus — the oldest woman to make the last four since Martina Navratilova in 1994 — was unable to roll back the years one more time.