The goals were scored by Matt McKay, Bobbie Kruse, Mark Milligan and Tomi Juric.
In the 3rd minute Oman had the first shot on target, Raed Saleh's half volley from outside the penalty box was saved by goalkeeper Mat Ryan.
The Socceroos pressure paid off in the 27th minute when Massimo Luongo swung in a cross from the left which Trent Sainsbury headed towards goal, leaving McKay the simplest of finishes.
Luongo was again the provider in the 30th minute when Kruse took his through ball before firing it into the net through the legs of Ali Al-Habsi to make the score 2-0.
The home side went three up in first-half stoppage time when Tim Cahill was fouled in the box while trying to reach Kruse's cross, the referee awarded a penalty. Milligan stepped up to score and made the score 3-0.
Juric, who replaced Cahill after 50 minutes, added the fourth after 70 minutes, turning Mathew Leckie's cross into the net at the far post.
Australia will now play South Korea on Saturday in Brisbane to determine who finishes top of Group A.