Deans became the front runner for the position after New Zealand Rugby officials overlooked the Canterbury Crusaders chief for the All Blacks job when they opted to retain the services of incumbent coach Graham Henry.
And the Australian Rugby Union have now moved to make the 48-year-old the first non-Australian to take charge of the Wallabies.
ARU Chairman Peter McGrath was delighted with the appointment.
"Robbie comes with a superb record and I am delighted to announce he will be joining the ARU," he said.
"The ARU Board presented the selection panel with a brief to find the most outstanding candidate. We as a board consider this appointment satisfies that objective.
"The Australian public would expect nothing less from us and we see this as a new start for Australian rugby. In terms of our playing ranks, we are on the doorstep of generational change.
"We believe Robbie Deans is the man to move us into that new era. He has created history by becoming the first non-Australian to coach the Wallabies.
"We trust there are further historic achievements awaiting him and the Wallabies over the next four years on the road to the 2011 World Cup."
ARU Deputy Chief Executive Matt Carroll echoed McGrath's optimism over Deans' appointment.
"Robbie will have a major contribution to make to Australian Rugby," Carroll said.
"That will include a close connection with Super 14 coaches, community rugby and the ARU management team."