Dartnell had an 11-under 133 total at Royal Sydney. He shot a 4-under 68 on Friday before heavy rain made the course unplayable.
Australias Mathew Goggin (70) and Chris Gaunt (65) were tied for second with Zealands David Smail (68). Gaunt and Smail finished the round Saturday.
John Daly completed an even-par 72 to miss the cut for the third consecutive week on his three-tournament tour to Australia. He opened with a 78 on Thursday, making headlines when he smashed a spectators camera into a tree.