"I'm pleased to advise that Chris is off life support and has been able to communicate with his family from hospital in Sydney," Aaron Lloyd said in a statement.
"He and his family are thankful for all of the support and well wishes from everyone, and for the privacy they have been afforded. They request that this continues as they focus on his recovery moving forward."
Cairns, 51, had surgery in Canberra after a "major medical event" earlier this month but the seriousness of his condition required him to be transferred to St Vincent's for another operation.
New Zealand media reported Cairns had suffered an aortic dissection - a tear in the body's main artery.
Cairns played 62 tests, 215 one-day internationals and two Twenty20 matches for New Zealand between 1989-2006.
His father Lance also played cricket for New Zealand.
Cairns has lived in Canberra with his wife and children for several years.