The former prime minister known for his hard-line stance on immigration was asked about Australia's points-based migration system.
"The great thing about the points system is that it attempts to ensure that everyone coming as a permanent resident and prospective new citizen of our country is capable of making a contribution," Mr Abbott told the mostly conservative crowd.
"The best way to ensure that that is the case is if you are coming to do a job from day one, pay taxes from day one, integrate with your work mates from day one."
Immigration officials in Australia assess skilled worker visa applications awarding points for proficiency in English, work experience and age.
Mr Abbott advised Britain to consider limiting the number of migrants it allowed in post-Brexit.
"You'd probably have to put a cap on numbers because Britain is such a desirable location and you don't want the place swamped with people trying to make a new life here."
The former Warringah MP who lost his seat at the May election delivered his Brexit speech as Mr Johnson threatened to call a snap general election next month if parliament rejects his Brexit speech.
"I have long wanted to make a serious speech about Brexit, I never imagined it would turn out to be at such a fraught time," Mr Abbott said.
He backed Mr Johnson to win an election.
"If it is an election that pits the parliament versus the people and the people's champion then I know which side I'd rather be working for."
Quoting the bible, Mr Abbott said those fighting for Britain to remain a part of Europe would fail.
"They will fail though because in the end there won't be enough of them to usurp a democratic vote, to sacrifice their country for short term political gain and to put Europe before Britain.
"As the scripture says, he who puts his hand to the plougher and then turns back is not worthy of the kingdom."