All Asian Cup semi-finalists earn automatic berths to the global showpiece, with the losing quarter-finalists to play off for two more spots on the Gold Coast next week.
Australia midfielder Alanna Kennedy scored her fifth goal at this year's Asian Cup in the ninth minute against the North Koreans, while captain Sam Kerr doubled the Matildas' lead just after the break before Chae Un-Yong pulled one back.
Australia will meet the winners of the match between defending champions China and Taiwan, who clash at the same Perth Rectangular Stadium on Saturday.
"I felt it was a really good team performance, defensively," said Kerr. "The crowd was immense today, got us over the line. We're going to need them again in the semi-final."
Kennedy has been in fine form for the 2010 champions and pounced when Kerr robbed opposing captain An Kuk-Hyang of the ball on the right side of the penalty area.
Kerr's cut-back was intercepted but the clearance fell to Kennedy who lashed a fierce strike from the edge of the box inside the right post.
Kerr stretched the lead with a poacher's goal in the 47th minute, swooping on a defensive mistake and thumping in another rising left-foot shot.
North Korea got their consolation goal in the 65th minute when Kim Kyong-Yong's cross found Chae who slid the ball home.
Midfielder Emily van Egmond became Australia's joint most capped player, joining Clare Polkinghorne on 169 appearances.