The firm said it sold more cars in the year to March 2017 than in the previous 12 months but that higher costs and currency fluctuations hit results.
The profit of 1.83 trillion yen ($16.1bn; £12.4bn) was down 21% from 2016-17.
Toyota has warned next year's profits will be even lower, due to the strength of the Japanese currency.
The carmaker's prediction is based on a forecast that the yen will average around 105 to the US dollar in the year through to March 2018, compared with 108 yen in the last financial year.
US investment
Toyota, which has lost its top-selling carmaker status to Germany's Volkswagen sold 10.25 million vehicles over the year, up from 10.19 million units a year earlier.
However income from those sales was slightly down at 27.6 trillion yen.
The carmaker has been struggling in the US, its biggest market. Sales fell in North America as it battled to meet demand for bigger cars such as sport utility vehicles, which have become more affordable to drive thanks to lower petrol prices.
Earlier this year Toyota said it would invest $10bn (£8.2bn) in the US over the next five years.
Source : BBC
