Muhammad Rizalman Ismail, a former defence staff assistant at Malaysia's high commission (embassy) in Wellington, escaped prosecution on attempted rape and burglary charges and returned to Malaysia in May after his country invoked diplomatic immunity.
But in an about-turn the foreign ministry said Muhammad Rizalman would be sent back "to assist in the investigation for the charges of burglary and assault with intent to commit rape".
"The Malaysian Government is of the view that this decision will provide an opportunity for Muhammad Rizalman to cooperate fully and assist the New Zealand authorities in the on-going investigations on the allegations made against him," it said in a statement.
The ministry said Foreign Minister Anifah Aman had conveyed the decision to his New Zealand counterpart Murray McCully, saying the decision was a "clear testament of the excellent bilateral relations".
The case has caused uproar in New Zealand, with the government facing criticism for failing to ensure the diplomat stood trial. The Malaysian government has also been accused of wrongly protecting Muhammad Rizalman.