Eight years after Sandpapergate, Bancroft was 156 not out after day one of the Sheffield Shield match against South Australia on Wednesday.
The 33-year-old opener led Western Australia to a commanding position of 3-304 after captain Hilton Cartwright won the toss.
The series decider against South Africa, which started on Tuesday, is the first time Australia have played a Test at Cape Town's Newlands ground since 2018.
Then, Bancroft was caught by TV cameras using sandpaper to doctor the ball while fielding.
He was banned for nine months over the scandal that rocked cricket, and has only played two Tests since. Steve Smith and David Warner were also suspended for their roles.
With Australia about to find out how their brittle top order will perform without Smith, who is injured, Bancroft roared back to form in Adelaide.
It is his first Shield ton of the season, after a top score of 16 in WA's previous two games.
Bancroft had hit 17 fours and a six in his 289-ball knock, which is his 21st Shield ton.
No.3 Jayden Goodwin made 108 in a 244-run stand with Bancroft that took the game away from the home side.
SA had started brightly, with Nathan McAndrew having Sam Whiteman caught by Mackenzie Harvey at first slip for one.
But Bancroft and Goodwin steadily took the game away from them. Goodwin was dropped on 76, eventually hitting 13 boundaries in his 222-ball innings before Brendan Doggett bowled him.
Cartwright made 27, caught behind off Wes Agar in the final over the day. Nightwatchman Corey Rocchiccioli saw off Agar's last five deliveries.
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