Prime Minister Bill English will travel to Europe for a week and a half on Monday, to discuss trade and security with other world leaders.
A statement from Mr English's office said he would visit Brussels to meet with three European Union presidents, and to London to meet with British Prime Minister Theresa May and the city's mayor, Sadiq Khan.
He would also meet with German Chancellor Angela Merkel in Berlin and Finance Minister Wolfgang Schäuble.
Mr English said the focus of his trip would be to start negotiations on a free trade agreement with the EU.
Belgium's deputy Prime Minister Didier Reynders arrived in New Zealand yesterday, partly to discuss the potential for such an agreement.
He said he would also tell Ms May he wanted the British and New Zealand governments to work towards a high-quality trade deal.
Trade Minister Todd McClay was expected to go with Mr English to Brussels, while Foreign Minister Murray McCully would join him in London and Berlin.
The Prime Minister is expected to return on 18 January, the statement said.