Genia, who is already seen as one of the stars of the Wallaby set up despite being just 22-years-of-age, replaces the unfortunate Luke Burgess at scrum-half, while former skipper Sharpe adds his considerable presence to the second row.
Robinson's return will perhaps be the most important for the Wallabies however, with the Waratahs prop returning to bolster a front row that was comprehensively out-scrummaged during the recent two-Test series with England.
First-choice hooker Stephen Moore is named among the replacements as he works his way back from a broken jaw that has seen him play just once since mid-May, meaning the inexperienced Saia Faingaa remains in the starting lineup.
James O'Connor moves out to the right wing, with Adam Ashley-Cooper starting at full back, while Quade Cooper maintains the fly-half berth as Matt Giteau starts at inside centre.
"It's really good to have a few of the troops back who have been unavailable to us," said Australia head coach Robbie Deans.
"Benn (Robinson) has had a little bit more background than Stephen (Moore), in terms of having been able to get underway a little bit earlier after his injury, which is why he's ready to start while we are easing Stephen back in off the bench.
"We've obviously been able to have a good look at both South Africa and New Zealand through their matches over the last two weekends.
"The imagery from those games has left our players in no doubt as to the magnitude of the task ahead.
"This competition features the top three sides in the world on the IRB rankings, and we are chasing the other two."
Australia picked up the wooden spoon in last year's competition but they haven't lost to the Springboks in Brisbane since 1971 and were 21-6 winners when the two sides met at the Suncorp Stadium last season.
But Deans insists his side won't be focusing on history this weekend - instead they'll just be looking to get their 2010 campaign off to a winning start against a Bok side playing their third successive away game in as many weeks.
"It will be about the here and now, as it always is," added Deans.
"Our team is significantly different even from that which played in Brisbane last year, as is theirs.
"The players who were involved on our side from that occasion can take confidence from that experience but it won't be worth any points for us on the scoreboard once this game starts.
"Although the Springboks improved significantly in the time between the Tests in Auckland and Wellington, they'll know that they have to lift again and will be determined to do so in order to go home with their foot back in the door as far as the Tri-Nations is concerned.
"They'll be well motivated for sure."
Meanwhile, the Boks have made four changes to the side beaten for the second successive week by the All Blacks as they look to return home with what could be a crucial victory under their belts.
Gio Aplon, who was on the bench for Saturday's 31-17 defeat in Wellington, starts in place of the suspended Jean de Villiers on the right wing, while Ulster-bound Ruan Pienaar comes in for Ricky Januarie at scrum-half.
BJ Botha is named ahead of CJ van der Linde at tight-head prop, with Ryan Kankowski replacing Francois Louw in the back row.
There are further changes on the bench where Flip van der Merwe, Dewald Potgieter, Francois Hougaard and Juan de Jongh all come to a side that bears little resemblance from the one that secured a series triumph over the Lions just over 12 months ago.
Adam Ashley-Cooper; James O'Connor, Rob Horne, Matt Giteau, Drew Mitchell; Quade Cooper, Will Genia; Benn Robinson, Saia Faingaa, Salesi Ma'afu, Dean Mumm, Nathan Sharpe, Rocky Elsom (captain), David Pocock, Richard Brown
Replacements: Stephen Moore, James Slipper, Rob Simmons, Matt Hodgson, Luke Burgess, Berrick Barnes, Kurtley Beale
Zane Kirchner; Gio Aplon, Jaque Fourie, Wynand Oliver, Bryan Habana; Morne Steyn, Ruan Pienaar; Gurthro Steenkamp, John Smit (captain), BJ Botha, Danie Rossouw, Victor Matfield, Schalk Burger, Ryan Kankowski, Pierre Spies
Replacements: Chiliboy Ralepelle, CJ van der Linde, Flip van der Merwe, Dewald Potgieter, Francois Hougaard, Butch James, Juan de Jongh