Rea came through for his first victory since May's Estoril round, and his sixth of the season, after timing his pitstop to perfection in a race that started on a wet-but-drying track and ended in almost bone dry conditions.
Yamaha's Toprak Razgatlioglu and the second Kawasaki of Alex Lowes completed the podium, while newly-crowned champion Alvaro Bautista could only manage a disappointing fifth for Ducati.
After qualifying took place in the dry, rain hit Phillip Island again in the lead-up to the race, prompting almost the entire field to equip wet tyres front and rear for the start - with only Go Eleven Ducati rider Philipp Oettl bucking the trend by opting for an intermediate at the rear.
Oettl plummeting down the field in a matter of corners made it clear that the wet tyres were the correct option for the start, as poleman Bautista led the early exchanges from Razgatlioglu and Rea.
Lowes soon made it a four-way fight at the head of the field as Rea took over out front from Bautista on lap 3 of 22.
Razgatlioglu then enjoyed a brief spell in front, passing Rea along the start/finish straight at the end of lap five before the six-time champion repaid the favour exiting the Southern Loop on lap 7.
Lowes followed Rea through to move into second, and at the end of the lap he was able to draft by his teammate to take the lead.
By now it was clear the track was rapidly drying out, and MIE Honda man Hafizh Syahrin was the first rider to come in to change to slick tyres.
Several other riders soon followed, and at the end of lap 10 Rea and Razgatlioglu both dived for the pits to get rid of their wet tyres, as Lowes stayed out on track in the lead ahead of Bautista.
Next time by, Bautista was in, leaving Lowes alone at the head of the field, and it wasn't until lap 12 that the Briton finally pitted.
In the meantime, Rea had pulled out a major advantage over Razgatlioglu in the pitstop phase and was comfortably leading the slick runners, while Lowes rejoined behind Bautista and Andrea Locatelli's Yamaha, having lost considerable time by leaving his pitstop relatively late.
BMW man Scott Redding tried to soldier on even further on his wet tyres, briefly leading before bailing on lap 14, while Pedercini Kawasaki rider Kyle Smith - in only his second WSBK outing - took the unorthodox decision to simply stay on his increasingly worn wet tyres until the chequered flag.
Smith therefore was credited for leading a lap before Rea inevitably passed him on lap 15, and the following lap Razgatlioglu eased by for second, albeit by now trailing Rea by five seconds.
From there it was plain sailing for Rea, who reeled off the remaining laps to finally end the worst losing streak of his Kawasaki tenure.
Lowes was able to battle his way back through ahead of Locatelli and Bautista, dispatching the latter with an exceptional move around the outside of Lukey Heights before Locatelli then demoted Bautista a further place.
However, fifth place for Bautista was still enough to guarantee Ducati its first manufacturers' title since 2011.
Garrett Gerloff (GRT Yamaha) beat Axel Bassani (Motocorsa Ducati) to top independent honours in sixth, while Xavi Vierge scored an important eighth place for Honda as it vies to beat BMW to fourth in the manufacturers' standings.
The German marque's top representative at the flag was Loris Baz in ninth, as Redding trailed home 16th after his very late stop and BMW's other works rider, Michael van der Mark, suffered a late crash.
Smith made it home in a heroic 12th place on his wet tyres, dropping behind the second Honda of injury stand-in Tetsuta Nagashima and Michael Ruben Rinaldi's Ducati late on.
Phillip Island WSBK: Race 1 results:
|11||21||Michael Ruben Rinaldi||Ducati||1'03.075|
|60||Michael van der Mark||BMW|
|View full results|