The American, 35, won 6-2 6-3 and will next play unseeded Croat Mirjana Lucic-Baroni, who beat fifth seed Czech Karolina Pliskova 6-4 3-6 6-4.
Konta, seeded ninth, went into the quarter-final on a nine-match and 18-set winning streak but came up short in her first meeting with Williams.
Williams is now two wins from claiming an Open-era record 23rd major title
"Johanna Konta has been playing so well," said the second seed.
"I was in the locker room watching her clean up her matches. She is a future champion here for sure, so I am pleased to get through this.
"I got a little frustrated with my serve, but I told myself 'don't get Babyrena' [Williams' angry alter-ego] and focused on enjoying myself out here. Today I felt I can do this, it is such a great opportunity for me."
Konta described facing Williams as the "best experience of my life".
In a match of big hitting and small margins, it was Williams who established an early control she would not relinquish.
The American's usually dominant first serve faltered as she made just 45%, but she returned brilliantly to break the Konta serve - the best on tour this season going into the match - four times.
Konta had the first chance but went long with a backhand on break point at 1-1, then found her second serve under greater pressure than at any stage of the tournament so far.
Williams looked razor sharp on return, with two thumping forehand winners setting the American on the way to a 3-1 lead.
More heavy blows brought a second break, and with it the set, in game eight to end a run of 18 straight sets for Konta stretching back to her warm-up win in Sydney.
Konta showed why she had been seen as a real threat by recovering from 0-40 early in the second set and then breaking to lead 3-1, but a loose game handed the advantage back and Williams raced through five straight games to victory.