The big-hitting Symonds was promoted to the starting side following the surprise retirement of Damien Martyn and the unavailability of all-rounder Shane Watson.
Symonds, also a handy spin bowler, will bat at number six, forcing Michael Clarke to move to five and Mike Hussey to four in the only change to the side that won the first two Tests to leave Australia one win away from regaining the Ashes.
Symonds has been an automatic selection in Australia's one-day team since his swashbuckling displays at the 2003 World Cup in South Africa but has failed to carry his limited-overs form into the Test arena, averaging just 19 with the bat in 10 appearances.
But Australia captain Ricky Ponting, a long-time supporter of Symonds, said he was confident the dreadlocked Queenslander was ready to realise his true potential.
''I'm pretty confident in him actually. I've watched him pretty closely over the last few days and he's extremely excited to be back amongst this group,'' Ponting told a news conference after training at the WACA on Wednesday.
''He might have thought his Test career might have passed him by a few months ago but...he's really excited about being back in the team again.
''Right now he feels better about his game than he probably ever has before and that's exciting for us.
''We all know what a great talent he is and he probably hasn't shown it to his capacity at Test level yet but we hope over the next few days we will see some of that.'' While the Australians announced their team a day before the match, England skipper Andrew Flintoff said the tourists were still uncertain about their lineup.
England have been heavily criticised by former players and media for choosing Ashley Giles ahead of Monty Panesar and sticking with the out-of-form pace duo of Steve Harmison and James Anderson instead of Sajid Mahmood. Giles, Harmison and Anderson have been largely ineffective against the Australians and with England 2-0 down and on the verge of surrendering the Ashes, the selectors are under pressure to make changes.
Flintoff said he would meet with coach Duncan Fletcher and senior players on the eve of the match to discuss the team but would not be drawn on whether changes would be made.
''These selection issues crop up but for four days of the Adelaide Test match it wasn't really an issue and then one and a half hours of almost crazy cricket everyone's looking at the side,'' Flintoff said.
''Everyone's staking a claim, everyone wants to play in this Test match. The lads have all put a claim in over the weekend.
''The bowlers bowled really well and in the nets today all the bowlers were running in and hitting the nets hard.'' England dominated large parts of the first four days in Adelaide before a dismal batting collapse on the last day gave the Australians the chance they needed to steal a victory.
Flintoff said the players had finally got over the disappointment and know they have to produce something special in Perth to keep the series alive.
''There's no lack of motivation, I don't think we need any more motivation than playing an Ashes series in Australia,'' he said.
''For all of us now, it's probably the biggest Test match of our careers so we don't need any more motivation, everyone's up for it in the dressing room.
''We've practised well over the past few days, obviously Adelaide's gone and we've moved on.'' Ponting said the Australians had banned any talk about regaining the Ashes to help guard against complacency.
''I've made it really clear to the guys I don't want any talk of that at all,'' Ponting said.
''As soon as you start looking too far ahead in this game it can turn back and bite you pretty quickly as we've all seen in the past.''
Australia: Ricky Ponting (capt), Matthew Hayden, Justin Langer, Michael Clarke, Mike Hussey, Adam Gilchrist, Brett Lee, Shane Warne, Glenn McGrath, Stuart Clark, Andrew Symonds, Mitchell Johnson (12th man).
England (from): Andrew Flintoff (capt), Andrew Strauss, Alastair Cook, Ian Bell, Paul Collingwood, Geraint Jones, Chris Read, Sajid Mahmood, Monty Panesar, Ashley Giles, Steve Harmison, Ed Joyce, James Anderson, Matthew Hoggard, Kevin Pietersen, Liam Plunkett.
Umpires: Aleem Dar (Pak), Rudi Koertzen (RSA).
Match referee: Jeff Crowe (NZ).