McLachlan, best known for roles in Neighbours and Home and Away, pursued the claim against Christie Whelan Browne after she alleged that he made sexually inappropriate comments and indecently assaulted her during a 2014 production of The Rocky Horror Show.
He has now hit back with his own allegations against the actress, which include her making crude and explicit gestures towards him while they were filming an episode of Australian TV show The Wrong Girl.
Documents submitted to the Supreme Court of New South Wales by McLachlan's lawyer claimed Ms Browne was "a notoriously foul-mouthed person who publicly distributed offensive matter", in reference to pictures posted on her Instagram page.
McLachlan - who earlier this week was cleared of sexual harassment claims made by colleagues on the set of TV series The Doctor Blake Mysteries - also alleged that Ms Browne used offensive language towards backstage crew on The Rocky Horror Show, and that she performed "indecent acts" on him.
Ms Browne was one of three stars from the stage production to accuse McLachlan of sexual harassment, indecent assault and bullying earlier this month, which led to the suspension of a new TV series he was set to appear in.
The 52-year-old - who recently reprised his role in another run of The Rocky Horror Show in Adelaide, only to leave after the allegations emerged - has denied all the claims against him.
He has also filed defamation proceedings against Australian outlets Fairfax Media and ABC for their reporting of the allegations, with Ms Browne having given a tearful interview to the latter to detail her claims against him.
The case will go before the Supreme Court in Sydney on 16 March.
