The 32-year-old, who endured a difficult summer back home, showed he hasn't lost his run-scoring appetite, compiling 163, off 267 balls with 19 fours and two sixes, to flay Glamorgan at Bristol on Friday.
The ever-solid opener was still being touted as making a potential comeback to the Australian Test team a few months ago before some indifferent form then a broken shoulder blade and nose suffered in a fielding collision swiftly ended those ambitions.
But with Gloucestershire, for whom he had shone in a third spell last summer, appointing him captain for 2025, Bancroft is evidently determined to repay their faith as he went past 11,000 first-class runs in his career with a 31st ton off 166 balls.
He shared a second-wicket stand of 230 with Ollie Price, who made 101 as Glamorgan paid the price for putting the hosts in, with Gloucestershire amassing 3-368.
Price was full of admiration for his skipper, who only arrived at Bristol on Wednesday after the long-haul flight and went straight to practice.
"He's continuing the same impact he had when he wasn't captain last year," said Price.
"He's such a high-class operator. Yeah, straight off the plane and straight in the runs, I don't think anyone's surprised."
Bancroft, fighting jet lag, had a bit of a dodgy start, surviving a couple of near-misses in the field and getting dropped - although a difficult chance - by wicketkeeper Chris Cooke on 48.
But after reaching 150 off 259 deliveries, it seemed only weariness beat him as he wafted at a wide ball from Ned Leonard and was caught behind.
Bancroft was not the only Australian county captain to thrive as Peter Handscomb continued his bright start as Leicestershire skipper at Grace Road with another half-century - ending up with 63 off 101 balls - against Derbyshire as they compiled 9-423.
Sussex expect much from their evergreen 36-year-old Aussie opener Daniel Hughes, who performed so well for them last season, and he'd looked on course for his first half-century of the season against Somerset at Hove before being trapped lbw by South African Migael Pretorius for a 93-ball 49.
In the morning, the Bathurst left-hander had put on a century second-wicket partnership with Tom Clark, which proved the bedrock of Sussex's total of 294 before Somerset struggled to 5-62 in response.
Dan Worrall's eagerly awaited seasonal debut, in the year he could become the first man since 1899 to play Test cricket for both Australia and England, got off to a bright start at the Oval.
The seamer bowled Hampshire opener Fletcha Middleton in his first spell (1-15) as champions Surrey tried to hit back after being bowled out for 253, with former England opener Dom Sibley carrying his bat for 100no.
Victoria's Fergus O'Neill had made a striking debut with the ball for Nottinghamshire last week but this time shone with the bat, coming in at 6-167 as they were struggling against Essex at Trent Bridge and knuckling down with 42 off 60 balls to help them recover to 8-328.
