Strong sales in North America and China failed to make up for sluggish demand in Japan and a stronger yen.
Profit in the last quarter at the firm, which recently announced that it would be building two new models at its vast UK plant at Sunderland, came in at ¥146 billion (£1.13bn), down from ¥173bn a year earlier.
Between April and September, Nissan sold 2.6 million vehicles worldwide. The car-maker is allied with Renault of France and its chief executive Carlos Ghosn also heads Renault.
Nissan, whose model line-up includes the Qashqai, X-Trail and GT-R, kept its full year forecast, through to March 2017, unchanged at ¥525bn.
Ghosn said: “Although Nissan faces market uncertainty and currency headwinds, we expect to continue to deliver solid earnings.”