Scott Morrison has warned government members that failure to regain focus after the Nationals leadership spill could cost the coalition re-election.
The prime minister addressed a joint coalition partyroom meeting via video link on Tuesday with the dust still settling on federal parliament's latest leadership coup.
Barnaby Joyce was sworn in as deputy prime minister at Government House hours earlier, completing a stunning political comeback.
Mr Morrison told coalition MPs and senators that having a clear plan, staying united and having an ability to "get stuff done" could deliver victory.
"If we fail on those things, we will hand the reins of government to those who are not fit to handle them and we will regret that forever," he said.
"We've got to focus. No time for individual agendas or pet projects."
He said voters would be sent to the polls "within the year".
With Mr Morrison still in quarantine, Mr Joyce returned to Question Time in the prime minister's usual place with a typically rambunctious performance.
He attacked Labor leader Anthony Albanese after being asked why he was focused on his own job rather than regional Australians.
"I am this man's biggest backer. I want you to be there for the long haul. I don't want you going anywhere," Mr Joyce shouted as he thumped the despatch box.
Mr Albanese told a Labor caucus meeting Mr Joyce had failed in his first stint as deputy prime minister and in all ministerial jobs he previously held.
The Nationals leader has taken the infrastructure, transport and regional development portfolios held by Michael McCormack, who he toppled in a leadership ballot.
Mr Morrison said Mr McCormack's performance to front Question Time after being defeated was "100 per cent classy" and would be important in healing divisions.
"The events can be disruptive but we're all professionals," the prime minister told colleagues.
Mr Joyce will now turn his attention to outlining policy and power demands in a new coalition agreement with the Liberals.
He is expected to solidify the Nationals' opposition to agreeing to a 2050 net zero carbon emissions target.
At the swearing-in ceremony, Mr Joyce was flanked by partner and former staffer Vikki Campion, who rose to prominence when the couple's affair was splashed across newspapers in early 2018.
Their two children Sebastian and Thomas also attended.
Mr Joyce's affair with Ms Campion triggered a firestorm of scandals including another woman making sexual harassment allegations against him, which he fiercely denies.
Labor questioned how women in regional Australia would receive his return after WA Nationals leader Mia Davies expressed disappointment with the change.
Deputy Nationals leader David Littleproud said election day would prove whether voters accepted the decision.
"As Barnaby said, he hasn't been perfect in the past. He's learnt from that," he told reporters.
"But I think it's important he's given the opportunity to prove that he has learnt and he needs to do that with actions. If he's given that opportunity, he'll provide it."
While Mr Littleproud will stay in charge of agriculture, Mr Joyce is expected to reward supporters with promotions when the ministry is reshuffled later in the week.
Australian Associated Press