The saga has mired the Perrottet government in an escalating "jobs for the boys" controversy since the former deputy premier's appointment was announced in June.
Mr Barilaro has been grilled by a parliamentary committee, who questioned his involvement in securing his girlfriend a job at Investment NSW.
Mr Perrottet said the scandal had left him disheartened, and he needed to seek advice on reports Mr Barilaro had met with one of his former ministers in June.
"The whole situation has been incredibly disappointing for everybody who has been involved. There's no doubt about that," Mr Perrottet told reporters on Tuesday.
"John Barilaro was a former trade minister and a former deputy premier, and that has been forgotten, I believe.
"As revelations have come out in respect of the process, I've been concerned and disappointed."
The premier referred to an independent review he instigated in June into the process, saying he expected to receive its findings shortly and was already working on his own recommendations.
A draft version of the review forced Penrith MP Stuart Ayres to resign last week from his roles as deputy Liberal leader and trade minister.
It raised concerns about whether Mr Ayres may have breached the ministerial code of conduct.
The premier announced on Tuesday that Bruce McClintock SC, a former ICAC inspector, would lead a review into whether Mr Ayres breached the code.
On Tuesday, News Corp reported Mr Barilaro met with recently sacked former fair trading minister Eleni Petinos in June, while the former deputy premier worked at development company Coronation Property.
The June 21 meeting occurred weeks before a building ban on a $500 million Coronation Property development was lifted.
Mr Perrottet told parliament he was not aware of the reports, would seek advice and take action if required.
The report claims former Building Commissioner David Chandler cited a "problematic" relationship with Ms Petinos in a resignation letter.
Mr Chandler resigned in June and will conclude in his role in November.
On Monday, Mr Barilaro faced questions over recommending one of his former staffers for a job at Investment NSW, after it was revealed the woman went on to become his girlfriend.
The inquiry revealed he gave a professional reference for his former media advisor Jennifer Lugsdin when she applied for the job last year.
The inquiry is interested in whether Ms Lugsdin had any sway over Mr Barilaro's appointment during her tenure at Investment NSW, which ended before Mr Barilaro applied for the job.
Mr Barilaro said he reached out to Investment NSW chief executive Amy Brown, but stressed the pair were not involved when he made the recommendation, or when she worked for him.
"I put forward her credentials and thought she might be a good candidate," he said.
Mr Barilaro said he did not believe anything improper occurred, because Ms Lugsdin was not hired by the NSW government and was employed as a contractor by a recruitment agency.
She stopped working for the agency in December, before he applied for the role in January.
Mr Barilaro said the upper house inquiry had failed to produce any evidence of misconduct and only revealed he was the best man for the job.
NSW Labor leader Chris Minns said the government had been engaging in obstructionist tactics since the inquiry began.
"I mean, it's a bit ridiculous ... this is taxpayer money. We need to know how it's been spent," Mr Minns told ABC TV on Tuesday.
"Circumstances around this appointment have been completely untransparent from the very beginning."
Mr Barilaro will be recalled to give more evidence to the inquiry on Friday.
