Mike Pezzullo has been sacked as head of the home affairs department after a code of conduct breach finding.
Mr Pezzullo was stood down after leaked messages revealed the secretary repeatedly inserted himself into the political process.
The governor-general in council terminated his appointment on Monday.
The texts revealed he lobbied for his department and pushed his personal views, in breach of public service standards, across a five-year period.
It is not suggested the messages show corrupt or illegal conduct.
Home Affairs Minister Clare O'Neil referred the matter to the Australian Public Service Commissioner after concerns were raised following media reporting of the messages.
Lynelle Briggs, who headed the inquiry, found he breached the code of conduct on at least 14 occasions in relation to five overarching allegations.
The allegations included that he used his duty, power, status or authority to seek to benefit or advantage himself, engaged in gossip and disrespectful critique of ministers, failed to maintain the confidentiality of sensitive government information, failed to act apolitically and failed to disclose a conflict of interest.
Ms O'Neil told parliament the move to sack Mr Pezzullo showed the government had a "profound respect" for the integrity of the public service.
"We value proper process, we value the integrity of the Australian public service - indeed we insist on it," she said.
The Community and Public Sector Union welcomed the decision to sack Mr Pezzullo.
CPSU national secretary Melissa Donnelly said his position was untenable with his reported conduct going against impartiality principles.
"The termination of Michael Pezzullo as secretary of the Department of Home Affairs is an appropriate and necessary step," she said.
The public service code of conduct needed to apply at all levels of employment, from graduates to middle management and department heads, she said.
"Far too often we have seen everyday public servants being held to a higher standard than their bosses," she said.
Veteran bureaucrat Stephanie Foster will continue to act as secretary until a new head is found.
The text messages showed Mr Pezzullo using a political back channel to get the ear of two former prime ministers through Liberal powerbroker Scott Briggs.
He suggested some ministers be sacked and which MP should oversee his department.
The texts showed he wanted Peter Dutton, now the federal opposition leader, to become home affairs minister.
