The 50-year-old overcame Peter Dutton, who was the key challenger to incumbent PM Malcolm Turnbull, to win a leadership ballot by 45 votes to 40.
He is expected to be sworn in by Governor-General Peter Cosgrove after Mr Turnbull officially resigns.
Born in Sydney in 1968, Mr Morrison has been Australia's treasurer - the equivalent of the UK's Chancellor - since September 2015.
He was first elected as an MP in 2007 when he won the seat of Cook, located in the southern suburbs of Sydney.
Known to be a regular churchgoer, after last year's referendum on same-sex marriage, he would back a new "religious protections" bill to support churches who didn't want to offer gay weddings.
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