A deal struck between the factions of the NSW Liberal Party on Sunday paved the way for the Treasurer to take the helm of Australia's largest state, with Liberal moderate Stuart Ayres set to be his deputy leader.

Mr Perrottet's triumph came hours after he officially put his hat in the ring, following the shock resignation of Gladys Berejiklian on Friday after the state's integrity commission announced it would formally investigate her for potential breaches of public trust.

Under the deal, Environment Minister Matt Kean is set to be appointed Treasurer.

"We believe it is a team that will provide stability, unity and experience to continue the great work of Premier Gladys Berejiklian and our entire team to ensure that NSW comes out the other side much stronger," Mr Perrottet said on Sunday.

Mr Perrottet will become the 46th premier of NSW.

The Independent Commission Against Corruption is investigating whether Ms Berejiklian "exercised public functions" in a position of conflict given her secret five-year relationship with ex-MP Daryl Maguire.

Ms Berejiklian denied wrongdoing but said she had no choice but to resign, and will also soon vacate her role as Willoughby MP.

Mr Perrottet's announcement that he would seek to become the next premier followed behind-the-scenes factional wrangling for much of the weekend.

The Epping MP entered NSW Parliament in 2011 - then as the member for Castle Hill - and served as finance minister before becoming Treasurer.

The father of six is a member of the Liberal Party's right faction. If he succeeds in his tilt, Jobs Minister Stuart Ayres will serve as his deputy.

The Liberal party room will next meet on Tuesday.

"NSW will come through this difficult time just as it did last year, to not just recover but come out the other side stronger," Mr Perrottet said.

"That's all about ensuring we keep people safe, as we have, keep people in jobs, keep businesses open and importantly, get kids back to school.

"We are just a week away [from] beginning to open up our state."

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Former prime minister John Howard earlier threw his weight behind Mr Perrottet's tilt, saying he was driven and reform-focused.

"His background, his experience as Treasurer and, very importantly, his commitment to economic reform mean that he, of all of them, is the best person to take over the helm," Mr Howard said.

Mr Perrottet earlier on Sunday said he was flattered by the endorsement.

Planning Minister Rob Stokes is the only other senior NSW cabinet minister to throw his hat in the ring for the premier's job. It is not clear if Mr Stokes will stand aside now Mr Perrottet has nominated to become premier.

Attorney-General Mark Speakman said in a statement on Sunday he would not nominate for the NSW leadership but would remain in government.

Ms Berejiklian has been lauded by everyone from Opposition Leader Chris Minns - who said he "cannot fault her dedication and hard work" - to Mr Morrison, who praised her "heroic" qualities, since her resignation announcement.

Mr Perrottet on Sunday also labelled Ms Berejiklian selfless and dedicated, saying she had made NSW a better place through her work.

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