The 26-year-old prop has become one of the lynch pins of a much-improved Australian side, with his presence helping to steady a previously under achieving Wallaby scrum.
"It's disappointing news for Benn, disappointing news for the rest of the squad and for Australian rugby as a whole," said head coach Robbie Deans.
"Robbo's obviously been part of the group for a while, so you don't like losing blokes who have been in the nucleus.
"Obviously, it wouldn't have been our choice, but these things happen. The seemingly innocuous circumstances in which it occurred only adds to the frustration.
"But when the door closes for one player, it opens for another and I'm sure the other front rowers we have will step up to fill the void Benn leaves."
Robinson sustained the setback in training yesterday, with scans earlier today showing a tear to his anterior cruciate ligament.
The prognosis will see the Waratahs' loosehead sidelined for at least six months, leaving the Wallabies with a significant void to fill this season and next.
Deans is expected to turn to the likes of Sekope Kepu, Ben Daley and James Slipper when it comes to replacing Robinson, although both Daley and Slipper are themselves recovering from shoulder and ankle injuries and are unavailable for the friendly with Samoa this Sunday.
And while Deans may have a few options available to him, the fact that the three most likely replacements only have 20 caps between them in comparison to the 42 won by Robinson makes for worry reading for the Wallabies.