Gladys Berejiklian has been elected leader of the NSW Liberal Party and will be sworn in as the state's 45th Premier.
At a Liberal party room meeting on Monday morning, Ms Berejiklian, 46, was elected unopposed, four days after Premier Mike Baird announced he was retiring from politics.
Finance minister Dominic Perrottet was elected deputy Liberal leader and is likely to become Treasurer in a forthcoming reshuffle.
Ms Berejiklian is due to be formally sworn in as NSW Premier at a ceremony at Government House on Monday afternoon.
The NSW Treasurer is expected to hold her first media conference as leader later on Monday morning.
In her pitch for the job, Ms Berejiklian has pointed to her six years of experience as a minister in the key portfolios of transport and treasury.
In apparent acknowledgement that the Baird government was at risk of losing touch with voters, she has noted that "the nature of politics is changing".
"People want to be heard - not just at elections but at all times," she said on Sunday night.
Ms Berejiklian has promised that as Premier she "will be working hard for everyone, listening to everyone and governing for everyone".
She has been reviewing some of the Baird government's most contentious policies as part of a "reset" towards the 2019 state election, most likely putting issues such as forced council amalgamations under scrutiny.
Mr Baird announced last Thursday he would retire from politics after nearly three years as Premier and close to 10 years in the Parliament.
He will hand his resignation as Premier to the Governor on Monday afternoon. A byelection will be held in his seat of Manly when he resigns from Parliament.