At least 28 major defence projects are a cumulative century behind schedule and 18 are over budget.
The troubled projects include Hunter class frigates, which are four years behind schedule and costing $15 billion more than anticipated, as well as battlefield airlifters, patrol boats, the battlefield command system, a series of satellite communications projects and the P-8A Poseidon aircraft.
At least $6.5 billion of project variations outside of the budget have also been identified.
Defence Minister Richard Marles said it would be challenging to rein in project blowouts, with defence spending placing significant strain on the budget.
"We've inherited a complete mess from the former government," he told ABC Radio on Monday.
Mr Marles blamed the troubled defence project pipeline on exchange rates and indexation as well as a revolving door of leaders.
"Goldfish lasted longer than coalition defence ministers and the result of that was a lack of oversight," he said.
Mr Marles said the Department of Defence was not responsible for the spending mismanagement.
"This is not the fault of the Australian defence industry, which does a wonderful job in serving the national interest," he said.
To fix the spending issues, the government has committed to a higher level of ministerial oversight.
This includes setting up an independent projects and portfolio management office within Defence.
Monthly reports on projects of concern and interest will also be handed to the defence minister directly.
"We are really confident that we can put in place a much better situation led by an active ministry," he said.
Mr Marles also said the culture needed to change from the top down to get projects back on track.
The government will also allocate extra resources to troubled projects to help get them off the ground.
When asked if the government would scrap the troubled French Taipan army helicopters in favour of the US Black Hawk, Mr Marles said he would not comment before the finalisation of a review under way.
The government has pledged to maintain its commitment to spending at least two per cent of GDP on defence, with expenditure set to increase to more than $80 billion by 2032.
DEFENCE PROJECTS DELAYED OR OVER BUDGET
* $44 billion Hunter Class Frigate program – construction delayed by four years and a $15 billion increase in expected costs.
* $1.4 billion C-27J Spartan Battlefield Airlifters – delivered four and a half years behind schedule and are unable to fly into battlefields.
* $3.7 billion Offshore Patrol Vessel project – running one year behind schedule.
* $356 million Evolved Cape Class patrol boats – running nearly a year late.
* $970 million Battlefield Command System – three years behind schedule.
* Several Defence Satellite Communications projects worth $906 million – running between two and four years behind schedule.
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