Senator McKenzie has become the fifth female member in the coalition cabinet.
The federal backbencher was elected as the National Party's deputy-leader in Parliament House on Thursday morning.
Nationals leader and deputy Prime Minister Barnaby Joyce announced “with great pleasure” that Senator McKenzie would assume the role after a party room ballot.
Prime Minister Malcolm Turnbull and Foreign Minister Julie Bishop congratulated Senator McKenzie on Thursday.
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She replaces Fiona Nash, who was ousted from parliament by the High Court when it ruled she had inherited dual-British citizenship from her father.
Senator McKenzie said Senator Nash was “a great friend and a colleague” who she couldn't “wait to get on the golf field with” as soon as possible.
“Now it’s about getting on with the job of delivering for regional Australia within the coalition government,” Senator McKenzie said.
Senator McKenzie grew up in Gippsland and entered parliament after the 2010 election when she was voted in as a senate representative for Victoria.
She is a well known firearms supporter, and she highlighted a fondness for clay target shooting.
Her office was in the regional Victorian town of Bendigo, but she came under fire in 2016 when it was discovered she lived in Melbourne’s inner suburbs and has never resided in Bendigo.
Senator McKenzie’s appointment completed reforms to the Nationals leadership team.
Mr Joyce returned to parliament on Wednesday after being sworn in again at Government House in Canberra.
He returned after an overwhelming win in the New England by-election on the weekend.
