Skipper Emma Kearney and Jenna Bruton topped the disposals for North Melbourne with 20 each.
GWS squandered two majors in the second quarter, one from Haneen Zreika who missed from point-blank range on a free run to the goal square.
The Kangaroos played the second half without forward Kaitlyn Ashmore, who failed a concussion test after suffering a nasty head clash.
Tempers flared midway through the third-quarter when North Melbourne’s Brittany Gibson pushed over Brittany Tully at a stoppage. Tully nailed the goal from the subsequent free kick to reduce the margin to 25-15. But the Kangaroos rallied and scored the game’s final two goals to maintain their unbeaten record in Tasmania.