Konstas plundered an unbeaten 151 from 167 balls in front of national selector Tony Dodemaide, as the Blues declared their second innings at 5-262 and set WA 364 runs to win.
Western Australia are reeling at 3-30 at stumps on day three at the WACA Ground.
Konstas also made 71 in the first innings in his first Shield outing on return from Australia A duties in India.
"I'm feeling very good, like I have a lot of clarity in the way I am batting," Konstas said.
"I feel like I am moving very nice. In the first game it was good to get some balls in and get a start.
"And just cashing in now with my start, so very happy."
Konstas was dropped from the Test team in July last year - after his whirlwind 60 on debut against India on Boxing Day 2024, he didn't pass 25 in his next nine innings before being axed.
But the 21-year-old's ton against WA is timely given ongoing uncertainty over a Test opening slot, surprisingly given to Nic Maddinson for the current series in South Africa.
On Wednesday, Konstas produced a free-flowing century - he reached the milestone from 136 balls.
The righthander then accelerated in an audacious knock highlighted by four sixes and 15 fours.
Told that Dodemaide was at the WACA watching on, Konstas said: "I didn't realise he was here, but it's good to score a few runs".
Konstas' fifth first-class century came as his teammates largely struggled - Ryan Hicks (35no from 31 balls) was the only other batsman to pass 22.
Spinner Corey Rocchiccioli claimed 3-90 from 19 overs and Jhye Richardson (1-41) and Liam Haskett (1-38).
WA's run chase faltered after a 29-run opening stand between Cameron Bancroft and Sam Whiteman.
Bancroft (11), Whiteman (17) and nightwatchman Rocchiccioli (duck) were dismissed in an eight-ball span, with Ben Dwarshius (2-5) and Jack Edwards (1-0 from four overs) the successful bowlers.
The Blues declared their first innings at 6-440, with WA making all out for 339 in their first innings.
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