The arrival of the furry marsupial comes as a conservation programme to save the animal -- which numbers just 250 in the wild -- gathers steam.
The joey emerged from its mother's pouch at the Richard Underwood Nature Refuge in Queensland state, which was established just eight years ago and is one of only two known colonies remaining.
Queensland Environment Minister Steven Miles said wildlife officers had been closely observing the mother for the past 10 months.
"This is the first addition to the reintroduced colony of northern hairy-nosed wombats in five years, and it indicates the new male brought in last year is settling in well."
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The only known colonies of the animal are both in Queensland -- at the Richard Underwood Nature Refuge and Epping Forest National Park.
When numbers dropped in Epping in 2009, the state government established the second refuge. The species' numbers have begun slowly recovering.
"This little joey is an important new arrival for the colony, and highlights that this refuge provides suitable conditions for successful breeding," said Miles.
Their main threats are wild dogs, disease and competition for food from kangaroos.