Sir John Kirwan will coach the side facing Australia in the Killik Cup match at Twickenham on November 1.
The 1987 World Cup winner will also take charge for the game against Leicester Tigers at Welford Road on November 4.
Auckland Blues head coach Kirwan wants to provide a Test-class examination for the Wallabies before they take on World Cup pool rivals England and Wales as well as facing France and Ireland.
And the former New Zealand wing is keen to maintain the status of the Barbarians as a unique side who bring together players from around the globe to “compete and play great footie”.
"In my view it’s the first Test of their tour. That’s what they’ll be expecting and that’s what we want to deliver,” said Kirwan, who will have Australia wing Nick Cummins in his side facing the Wallabies.
“It’s a privilege and a huge honour to be involved with the Barbarians again.
"I grew up watching the Barbarians score the greatest try ever and for them to survive and continue to thrive in the modern market place is so important. What they do is a very precious thing.
“Every year the Barbarians are put under pressure but it’s still a huge honour to play and they still compete with the very best.
“If you’ve played for club and country but haven’t played for the Barbarians you’re still missing something, and when people find out you’re the Barbarians coach they’re on the phone asking to play.”
The Barbarians will name the rest of their squad in the coming weeks before assembling in London on October 28.
Former Wales lock Phil Davies will coach the Barbarians later next month when they face the Combined Services at Bath on November 11.
More than 50,000 tickets have been sold already for the Barbarians v Australia at Twickenham on November 1 (2.30pm).
Tickets are still available from £30 for adults and £15 for juniors (U16) at www.ticketmaster.co.uk or by calling 0844 847 2492.
