Pini made history last week winning his first ever gold medal at an Australian national championships.
His last event will be the 50m backstroke on Wednesday.
Team PNG has four swimmers taking part at the championships - Ryan Pini, Samuel Seghers, Ryan Maskelyne and Barbara Vali-Skelton.
Seghers also has two events left, the 50m freestyle and 100m fly on Tuesday.
Maskelyne has the 50 breaststroke also on Tuesday.