Williams converted four of her five break points, while Strycova failed on all three of her chances.
Simona Halep dispatched Elina Svitolina in straight sets to reach her first Wimbledon final, winning 6-1 6-3 in just over an hour.
"I actually didn't think about it since it's really not about 24 or 23 or 25". It's really just about going out there and giving my best effort, no matter what.
"I was calm today", she said, then rolled her eyes and added: "It's a day-to-day basis with me".
Serena Williams (USA) at a change of ends during her match against Barbora Strycova (CZE) on day 10 at the All England Lawn and Croquet Club.
The pair have met three times before, with Williams winning every time including in the first round at Wimbledon in 2012. Nine different players have won the last 10 Grand Slam tournaments, and this year's theme seems to be upsets - most of Wimbledon's usual suspects are already eliminated.
The outcome ended Britain's hopes of a first women's singles champion here since Virginia Wade in 1977.
Williams has been on the prowl for the historic title since the 2017 Australian Open, which she won shortly after learning she was pregnant.
The Wimbledon final comes shortly after Harper's Bazaar published an essay by Williams in which she detailed her feelings after last year's contentious U.S. Open final against Naomi Osaka, which she said led her to seek therapy.
Although Svitolina stayed with Halep for the first part of the second set, the self-belief and fight had gone and when the Romanian broke for 4-3 it was game over.
"She is in a good place at the moment, she is happy, has a house, her husband is here her daughter is here and she is pain free", he said.
On Saturday, Williams will take on No. 7-seeded Simona Halep of Romania, a 6-1, 6-3 victor over No. 8 Elina Svitolina of Ukraine under a cloudy sky at Centre Court.
Svitolina, being watched from the players' box by her English coach Andy Bettles and French boyfriend and ATP star Gael Monfils, briefly raised her game to break back. "But now I feel stronger, mentally, facing her".
"Twenty-four will mean that she will equal the record of all time. and that's why she came back to playing tennis after having a baby and so many medical complications". We will see what is going to happen.
Considering Halep developed her baseline skills "on the sand and also in the water of the sea", it is perhaps unsurprising that she was initially considered something of a claycourt specialist. She'll also try to extend points and move Williams around the court; Halep's exceptional defense can put pressure on Williams and force her into mistakes.
Couple opens up about 'heartbreaking' IVF mix-up
Anni and Ashot Manukyan are one of three couples whose embryos were involved in the mix-up, according to their lawyer Adam Wolf. They had to sue in family court to obtain custody, and the boy was six weeks old by the time they got to see him, they said.