Global economic growth remained moderate, but the outlook has been revised down due mainly to weaker activity in the developing economies, the bank said in a statement.
Domestically, the economy was adjusting to the sharp decline in export prices, and the consequent fall in the exchange rate, it said.
Several factors continued to support growth, including robust tourism, strong net immigration, the large pipeline of construction activity in Auckland and other regions, and the lower interest rates and the depreciation of the New Zealand dollar.
"While the lower exchange rate supports the export and import-competing sectors, further depreciation is appropriate, given the sharpness of the decline in New Zealand's export commodity prices," Reserve Bank Governor Graeme Wheeler said in a statement.
Today's rate cut was widely anticipated in the financial markets and follows two rate cuts of 25 basis points each in June and July.