Businessman John Symond hosted the exclusive fundraiser, attended by 15 senior business executives, in his Point Piper home on Wednesday to raise funds for Mr O'Farrell and the Liberal party, the Daily Telegraph reported on Thursday.
Under the Keneally government's campaign finance reforms, annual donation caps of $5000 to parties and $2000 to individual candidates or MPs will come into effect on January 1.
Ms Keneally said Mr O'Farrell was "blatantly flouting donations laws coming into effect in five weeks".
"Barry O'Farrell's behaviour is totally unacceptable," Ms Keneally sid in a statement.
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"The Liberals are desperate to collect political donations before they are capped on 1 January.
"It is even clear that the business people involved in last night's function were uncomfortable with Mr O'Farrell's fundraising approach.
"The Liberals tried to find any excuse to resist campaign finance reform because they are addicted to donations.
"Now they've been caught out trying to have one last hit before the cut off."
The Liberals needed to "come clean" on whether they were still taking money from tobacco companies, gaming enterprises and certain pubs and clubs, Ms Keneally added.
