The 27-year-old departed for a career-high 224, caught behind off the bowling of Kane Richardson, his innings including 23 fours and five sixes.
Maddinson shared a 220-run opening partnership with Marcus Harris, who gave his chances of holding onto a Test opening spot a shot in the arm with a well-made 116.
After a lean Ashes series where he made just 58 runs from six innings, Harris returned to form in an innings that included nine fours and four sixes.
Victoria skipper Peter Handscomb, who won the toss on Thursday morning, was out for 30 shortly before lunch, caught at mid-on as he attempted to push the run rate along ahead of a declaration.
The Redbacks’ attack, which is without injured trio Joe Mennie, Chadd Sayers and Daniel Worrall, has struggled mightily with little help from a docile wicket.
Nick Winter is the pick of the bowlers with 1-71 from 25 overs, including three maidens.