Lost, confused and looking for its mum - that's how a tiny koala found itself in an Adelaide Hills backyard.

So when local Henry let his dog 'Tony' out on Sunday morning, the joey found a perfect motherly replacement.

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Henry walked out into his Stirling backyard to discover the baby had made itself at home, nestled inside Tony's fur.

Clinging on for dear life to its new ride, the joey was not about to get off without a fight.

Tony was a little unsure about his furry passenger. Credit: Supplied / 7NEWS

While the koala was enjoying the experience, Tony didn't look so convinced.

He trots around with the baby on board for a minute before deciding he'd had enough of his furry passenger.

The tiny joey clung on for dear life to its motherly replacement. Credit: Supplied / 7NEWS

Eventually, he gets the koala back on the ground.

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Henry says koalas are fairly common in the area, but it's the first time he's seen anything like this.

He says the baby climbed back up into nearby trees - presumably to return to his real mother.

While Tony was a little confused by the furry backpack, Henry says he's recovered well.