Ken McClure (46) and Todd Astle (45) showed some resistance but the innings really came alive when Henry strode to the crease with the hosts on 179-7.
The Black Cap proceeded to plunder an unbeaten 75 from 52 balls, smacking 12 fours and two sixes to set a new high score and register the second half century of his professional career.
And once he was left stranded short of a possible century as Canterbury were dismissed for 310, Henry headed to the bowling crease and took 3-22 to leave Central Districts with a real fight on their hands on the fourth day.
Leaders Auckland will also face a final day battle to maintain their perfect record, with Northern Districts holding a lead of 256 runs and possessing four wickets in hand heading into today.
The hosts crumbled from 312-4 to 380 all out at Eden Park Outer Oval as the Knights bowlers, led by Scott Kuggeleijn (4-108) and James Baker (3-86), dispatched the lower order with few difficulties.
Northern Districts held a one-run lead at the halfway mark before Bharat Popli (68) and Corey Anderson (83) combined to grow that slight advantage.
The first innings centurion and the returning Black Cap shared a 125-run partnership for the fourth wicket to position the visitors nicely despite the menace of Mitchell McClenaghan (4-56).
At the Basin Reserve, an unbroken 223-run stand between openers Michael Papps (125) and Luke Woodcock (91) put Wellington in complete control against Otago. The home side will resume holding a lead of 272, with a declaration from Papps appearing imminent.