Northern paceman Trent Boult dismissed Aaron Redmond without scoring and Greg Todd for one inside the first 15 balls and from that moment the hosts never regained the front foot.
They struggled to 167 in brilliant conditions at Molyneux Park, dismissed with more than six overs remaining.
Northern opener Hamish Marshall was trapped lbw for a duck but the run chase was plain sailing from there, with opener BJ Watling and Michael Parlane seeing them coast to 171 for one.
They had nearly 15 overs to spare, meaning they will pick up a bonus point as well.
Watling was shaky early but blossomed to reach 83 off 119 balls, pulling the winning runs for four in imperious style. He hit 10 fours and a six.
Veteran Parlane was steadier in compiling 65 off 90 balls, an innings that included two sixes.
None of the Otago bowlers threatened although English import Dimitri Mascarenhas was tight, conceding 14 from his six overs.
Only young opener Shaun Haig showed any fight for the hosts, reaching a classy 79 off 112 balls. He was the second-last batsman dismissed, run out in the 43rd over.
Boult produced brilliant figures of two for 10 off eight overs while Joseph Yovich put the clamps on the Otago innings, taking three for 30 off 10.
Bowlers from both sides had wayward moments, with Northern sending down 13 wides and Otago 17.