The ruthless world number two proved one step too far for unseeded Croat Mirjana Lucic-Baroni, whose fairytale tournament was finally ended in a crushing 6-2, 6-1 defeat in just 50 minutes.
In swatting aside the 34-year-old, in their first meeting since 1998, Serena, 35, stayed on track for a seventh Australian title which would take her past Steffi Graf's Open-era record of 22 major wins.
She has refused to talk about the possibility of finally surpassing the German, but now has a golden chance of further cementing her place in history.
Only Venus stands in the way after the elder Williams rolled back the years to beat fellow American Coco Vandeweghe 6-7 (3/7), 6-2, 6-3 in the other semi-final.
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It ensured another chapter in their eventful family history as they meet for their ninth Grand Slam final on Saturday, eight years after the last. Serena holds a 6-2 advantage.
"I didn't watch (Venus). Obviously I was really proud, she's an inspiration, my big sister," said Serena.
"She's my world, my life, she means everything to me. I couldn't be happier for us both to be in the final. It's the biggest dream come true for us."
"Mirjana is an inspiration, she deserves all the credit today. To get this far, after everything she has gone through, that just inspires me."
- One-way traffic -
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Despite her serve not being up to scratch in Melbourne until now, Williams has so many other weapons in her armoury that her opponents have been unable to cope.
Lucic-Baroni was no different.
Her left thigh was again heavily strapped and the problem put her at an immediate disadvantage, restricting her movement against a player known for her pounding forehand winners.
She consolidated her lead by holding serve again, and a Lucic-Baroni double fault handed her a 4-1 lead.
It was one-way traffic as the second seed asserted her authority, unloading some powerful groundstrokes to unsettle the Croat and easily take the first set in 25 minutes.
The second set went the way of the first, with Williams crushing Lucic-Baroni's serve to again break in the third game.
She was broken again in game five as her magnificent run drew to a close and Williams moved into her 29th Grand Slam final.