Planning Minister Rob Stokes and Treasurer Dominic Perrottet have emerged as the top contenders for the position, but Attorney-General Mark Speakman is also considering a tilt.

Ms Berejiklian announced her resignation on Friday after the state's corruption watchdog disclosed the 51-year-old was under investigation for potential breaches of public trust.

She will remain premier until the Liberal Party elects a replacement, with Pittwater member Rob Stokes quick to stake his claim.

The 47-year-old - who has been described as a key ally of Ms Berejiklian - is the first cabinet minister to publicly announce he will contest the leadership, saying "many colleagues" had encouraged him to run.

"My track record during my time in public office makes me the best candidate to lead the NSW government," he said in a statement on Saturday.

"I have the right balance of experience, vision and integrity needed during this crucial time in our history, as we continue to respond to and recover from the pandemic."

Mr Stokes has promised to abide by the roadmap out of COVID-19 lockdown Ms Berejiklian unveiled only weeks ago.

Restrictions are due to ease across NSW gradually from October 11 after more than 15 weeks of lockdown for Greater Sydney.

Former prime minister John Howard is backing Dominic Perrottet as Ms Berejiklian's successor.

"A number of talented MPs have been suggested as her replacement (but) I hope that Dominic Perrottet becomes the new Liberal leader, and therefore the next premier of NSW," Mr Howard said in a statement.

"He has the intelligence, experience and commitment to reform that the state needs at this time."

Mr Perrottet, 39, has said he too enjoys support within the party, telling the ABC he has received "strong feedback" from his colleagues.

However a third cabinet heavyweight, Attorney-General Mark Speakman, has also indicated he will vie to become premier.

"I'm heartened by the encouragement I've received from colleagues to nominate and I'll have more to say tomorrow," the 61-year-old said in a statement.

Other possible candidates include Environment Minister Matt Kean, Tourism Minister Stuart Ayres and Transport Minister Andrew Constance.

Whoever succeeds Ms Berejiklian has a tough act to follow.

Prime Minister Scott Morrison led the tributes on Friday, lauding her "heroic" qualities, while Mr Howard said the state would grieve her departure.

Even state Opposition Leader Chris Minns declined to sink the boot in over her demise.

"There's plenty of time for politics ... once the pandemic is over," he said.

"I cannot fault her dedication and hard work on behalf of the people of NSW, particularly over the last 15 weeks.

"I'm sure that ... will not be forgotten."

Meanwhile supportive constituents have gathered outside Ms Berejiklian's home with flowers and balloons, while others put up handmade signs at her office reading "We love Gladys" and "Long live Gladys".

Ms Berejiklian's leadership endured bushfires, drought and storms, and she navigated COVID-19, but after four-and-a-half years in the top job, she could not escape the ICAC.

The anti-corruption watchdog says it is investigating whether she "exercised public functions" in a position of conflict given her secret five-year relationship with ex-MP Daryl Maguire, revealed at its hearings in late 2020.

Mr Maguire is accused of abusing his public office between 2012 and 2018.

A teary and at times angry Ms Berejiklian said on Friday she had "no option" other than to resign, but she continues to deny any wrongdoing.

She will also resign from parliament as soon as a by-election for her north Sydney seat of Willoughby can be held.

Australian Associated Press