Mr Turnbull had been under pressure from poor polling and what he described as an “insurgency” by conservative MPs.
Mr Morrison, the treasurer, won an internal ballot 45-40 over former Home Affairs Minister Peter Dutton – who had been Mr Turnbull’s most vocal threat.
Mr Turnbull is the fourth Australian PM in a decade to be ousted by colleagues.
“It has been such a privilege to be the leader of this great nation. I love Australia. I love Australians,” he said on Friday.’