McKenzie succeeds Robbie Deans in the post with the New Zealander resigning in the wake of the Wallabies' series defeat to the British and Irish Lions. McKenzie made 51 appearances for Australia at prop and was part of their 1991 World Cup-winning squad before carving out a successful coaching career at home and overseas.
He is excited at the opportunity to coach his home country and is hoping to make an immediate impact. "I'm really pleased to be able to accept the job of Wallaby coach," he said. "I'm pretty proud right now, pretty privileged to be able to get that opportunity."
McKenzie added: "Right here and now I've been asked to do a very specific job, that job starts in five weeks' time. There's no better coaching assignment than to pit yourself against the All Blacks.
"I've played and coached in a bunch of Bledisloe Cup games (as A team coach) and to get another crack at the All Blacks is terrific. I'm really looking forward to the challenge of taking them on and from that, good things can flow.
"It's a really important time in Australian rugby. On the field, people will worry about where the Wallabies are at. I'm looking forward to the challenge of making a difference in that and in the game as a whole."
Deans opted to quit following Saturday's 41-16 third Test mauling by the Lions which handed the tourists a 2-1 triumph. An Australian Rugby Union statement read: "Qantas Wallabies head coach Robbie Deans has announced this morning he is stepping down from the role effective immediately."
The governing body had already been reviewing Deans' performance with his contract due to expire at the end of the year.
"We have been conducting that due diligence over the last few months, taking into account broad criteria for coach selection," ARU chief executive Bill Pulver said. "Consideration was given to leadership skills, discipline, coaching capability, coaching records, and important factors such as character, values and style of play."
Deans led the Wallabies in 74 Tests having been appointed early in 2008. He said: "I wish to take this opportunity to thank everyone involved in Australian rugby for their support through the duration of my tenure. It has been a rewarding five years and I am proud of all that we have achieved."