The opener has been one of the form batsmen in the competition and entertained a crowd of 1130 with a clever knock as Otago compiled 191 for four at the University Oval yesterday.
Redmond's opposite Brad Wilson kept Northern Districts in the hunt with a superb innings of 91 from just 53 balls.
But when Otago skipper Craig Cumming sneaked a delivery past his defence, the innings deteriorated rapidly with four wickets tumbling in two overs.
The part-time bowler missed out with the bat but had a fine day at the bowling crease, taking four for 23 from three overs to help snuff out Northern's chase.
The visitors reached 170 for eight with some lusty hitting at the death by Daniel Flynn.
That helped close the gap in what was otherwise a convincing victory.
The win means Otago has won four of its five games and is well placed to make the final with three round-robin games remaining.
While Cumming claimed four wickets - two in two deliveries - and English all-rounder Dimitri Mascarenhas walloped a rapid half century, it was Redmond and his opening partner Hamish Rutherford who set the victory up.
The pair have been in good touch, scoring four 50-run plus partnerships in five innings.
Yesterday, they added 50 in just 19mins and 26 balls in an opening stand of 63 runs.
"I think that certainly set the game up," Otago coach Mike Hesson said.
"Aaron and Hamish have played exceptionally well.
''Aaron was in sublime form [yesterday] and just played great cricket shots.
"That was a superb twenty/20 innings."
Rutherford was undone on 27 when he mistimed a pull shot but Redmond continued the onslaught, whacking four sixes and seven fours.
The innings featured some exquisite cricket shots but there was also a liberal sprinkling of invention as he lapped and dabbed the ball into gaps.
He was in no mood to let veteran spinner Bruce Martin settle and went after the bowler from the moment he was introduced.
Martin eventually got his man but not before Redmond had put Otago into a solid position.
Mascarenhas took the long handle, whacking three sixes and five fours on his way to 55.
But once he got out the innings lost some momentum and Greg Todd and Warren McSkimming could only manage three runs from the last over.
Wilson might have got within sight of a twenty/20 century but his innings should have ended on five when Sean Eathorne got both hands to thick edge at short third man.
Wilson's effort was largely a lone hand, though.
And as the wickets kept tumbling and the run rate spiralling upwards, the situation became more and more desperate for the visitors.
Wilson's wicket triggered a collapse with Joseph Yovich stumped the next ball, thanks to a sharp piece of keeping by Derek de Boorder and an in-ducker from Cumming.
The same duo combined to remove Bradley Scott three overs later.
But before Scott went, Northern lost another two wickets in the 17th over with Kane Williamson offering a catch and Te Ahu Davis suffering the indignity of being run out without facing a ball.
Northern went from 129 for three, and in with a chance, to 136 for seven and out of the race.
Needing an impossible 42 off the last over, Flynn treated the crowd to three sixes as his side plundered 20 off the last over.
