He suffered serious injuries to his arms and shoulder and was taken to Westmead Hospital.
Rosniak, 36, is best known for playing ”Warney” on Packed to the Rafters from 2007 -2012. He also played Squizzy Taylor on Underbelly: Razor, and had roles in Laid, Police Rescue, Rush, Home and Away and the film Animal Kingdom.
Penrith police Inspector Garry Sims said, ”The white Mitsubishi van was travelling north on Mulgoa Road when control was lost, causing it to cross onto the southbound lanes and it flipped over onto the roof.”
A witness also told News Limited “….the driver had been thrown about 10 metres from the vehicle, so it looks as if it could have been worse had he been inside.”
Police said Rosniak was the sole occupant of the vehicle and no-one else was injured.
A spokeswoman for Channel Seven was unavailable for comment.
Updated: His condition is upgraded to stable.