"I don't think the implications for our economy will be that significant," he said.
Once the process goes through, New Zealand would have to renegotiate trade and migration access, but Mr Key said he'd had assurance from both European Union and United Kingdom officials that the status of access for New Zealand goods and people would not change until new conditions could be negotiated.
"The most immediate impact on New Zealand is likely to be the turmoil in the international markets and the uncertainty in terms of the likely outcome for Europe and the UK's economy."
He addressed media at Auckland's SkyCity following the United Kingdom voting to leave the European Union last night.
Mr Key said the reaction in the markets was down to the decision for the UK to leave the EU being unexpected.
He added things would return to normal levels over time and that the New Zealand economy was quite diverse so he expected only a small impact here.
Mr Key said he was yet to contact David Cameron since his resignation as British Prime Minister.
