PNG got away to a 14-0 lead at the break, thanks to tries from Gairo Kapana and Eugene Tokavai.
More points came in the second half through tries to Freddy Rova, another to Kapana and William Tirang.
The Pukpuks will now face USA in the semi-final at 12:25pm. In the other semi-final, Argentina will play Canada. This match kicks off at 12:03pm.
Winners from both semi-finals will play off in the Challenge final at 3:33pm this afternoon.
The HSBC World Rugby Sevens Series 2018- Hamilton is being played live on TVWAN Action.