On Monday, Rick Maddison fatally shot Senior Constable Brett Forte after the police officer intercepted his car in Queensland.
He fled to a nearby farmhouse and spent the night in a stand-off with police.
Maddison was killed by authorities after fleeing the house and firing on police, Queensland Police Assistant Commissioner Tony Wright said.
"He has been challenged by police at that point in time - he has fired at those police," he told reporters on Tuesday.
"Specialist police have returned fire. The male person has been shot and that male person has been declared deceased at the scene."
Mr Forte was killed after intercepting Maddison, who police had described as a "wanted person", about 14:20 local time (04:20 GMT) on Monday.
Authorities had set up an exclusion zone around the farm and began negotiating with Maddison at midnight.
The confrontation happened just after 11:00.
On Monday, Queensland Police Commissioner Ian Stewart said he wanted to resolve the siege "as peacefully as humanly possible".
Residents nearby residents were ordered to evacuate their homes on Monday evening.
Mr Forte was a husband and father who had been a police officer for more than 15 years, authorities said.
"It is so distressing - not just to the police service - but to the community, that we have lost a fine police officer," Mr Stewart said.
Queensland Police Union president Ian Leavers said the officer was shot "simply trying to apprehend a wanted person".
"It could have been any one of us anywhere in Australia," he told the Seven Network.
"Our thoughts are with his wife and his three children. He has got a daughter and two sons."

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Steven MacLean's second half finish deservedly earned three points and means the visitors leapfrog Motherwell, who lost to Aberdeen.
"It's a 38 game league," Wright told BBC Scotland.
"We try and prepare them for the whole season and the last few seasons we've tended to finish strong."
Saints have won both matches since the Premiership split in half for the final run in and visit Motherwell next weekend.
"Last season after the spilt we were unbeaten and that's difficult to do as you're playing against the sides that have been at the right end of the table all season," added Wright.
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"We have a tough game coming up against Motherwell but we're in a nice position at the minute with three games to go.
"We knew it would take a good performance coming up here, particularly with the result Ross County got last week at Celtic
"Throughout the 90 minutes we controlled quite a huge chunk of that and never looked in any real danger.
"We passed the ball well, defended well, got the goal at the right time and had not too many problems to deal with so I'm a happy manager."
The only disappointment for Wright was another injury to Chris Millar who had to be replaced before half-time after suffering a calf injury.
"Chris has a problem," explained Wright. "It's not the problem that's hampered him this season, it's a calf problem as well.
"It doesn't look too serious so hopefully he'll get back for a couple of the games we've got left."
Ross County manager Jim McIntyre saw his hopes of finishing fourth severely dented and was in no mood to gloss over an abject performance from his side.
"We were really poor," he said. "I would put that up there as the poorest performance this season.
"It looked as if we had nothing to play for. St Johnstone looked as thought they wanted it more.
"It was a scrappy goal to lose the match but the best team won.
"For the first time this season we didn't have a period in the game where you thought 'we're going to get a goal here'.
"We just had most of the players off the pace of the game, it's as simple as that. We didn't start well and we didn't recover from that.
"We've got professional pride and placing money to play for and that's still achievable but it's going to take a hell of a lot better performance than what we saw today."
A man who killed a policeman before holding authorities at bay for 18 hours has been shot dead in Australia.
[NEXT_CONCEPT]
On May 7 it's the general election, where adults across the country will decide who they want to run the UK.
[NEXT_CONCEPT]
Manager Tommy Wright is sure St Johnstone can hang on to fourth place in the Premiership after picking up a 1-0 win at Ross County.