The Socceroos moved onto six points from two games with a commanding win in Saudi Arabia after Frank Rijkaard's underwhelming Green Falcons
The result means Australia have six points from two games, having already achieved victory in a fixture which was expected to be their toughest of the third round.
In truth, Frank Rijkaard's Saudi Arabia failed to cause Australia too many issues excluding a brief period in the second-half after dragging a goal back at 2-1.
Rijkaard and Australia coach Holger Osieck had both pulled surprises prior to the game, leaving out their respective side's attacking stars Yasser Al-Qahtani and Tim Cahil and they appeared to be missed with few chances created in the opening half hour.
However, Australia became more threatening with Matt McKay and Brett Holman both curling efforts wide before Kennedy headed the visitors ahead.
The Nagoya Grampus striker rose above Saudi Arabia defender Osama Hawsawi to power Luke Wilkshire's right-wing cross past the scrambling keeper Hassan Al-Otaibi on 40 minutes.
After the break, impressive left-back Michael Zullo drove down the flank before Carl Valeri unleashed an effort which was tipped over the bar by Al-Otaibi before Saudi striker Naif Hazazi headed straight at Australia keeper Mark Schwarzer.
On 56 minutes, Kennedy doubled Australia's lead when Brett Holman swooped on a poor pass by Al-Otaibi before setting up the beanpole striker who coolly slotted the opportunity.
Saudi Arabia came back into the contest on 64 minutes when Zullo bundled over Hazazi inside the box.
Nasser Al-Shamrani stepped up for the resultant spotkick, seeing his initial effort saved by Schwarzer before poking home the rebound.
The Green Falcons rallied after the goal with a parochial crowd behind them, but Australia put the result beyond doubt when Kennedy earned his side a penalty.
Saudi defender Hamad Al-Montashari hauled the Aussie striker to the ground in the box and Wilkshire stepped up to smash home the spotkick to make it 3-1 on 77 minutes.
Hazazi cannoned a header into the crossbar late on, but Australia safely navigated the final 10 minutes to secure an invaluable three points.