A convicted child-sex offender found to have a soundproof cell in his Rosewood backyard has been evicted from Australia and returned to New Zealand.

New Zealand-born Brent Joseph Groves, 49, is living in Wellington after he was banned from Australia in April.

Groves, who moved to Australia in 1969, was jailed there in 2002 for drug offences and for indecently treating a child under 16.