The figure was 0.2 percentage points lower than the initial 0.4 percent reading offered by the state-run statistics agency in April.
Meanwhile, the country’s public debt stood at 48.9 percent of GDP last year, the Central Statistical Office said on Monday, confirming its earlier estimate from April.
Poland’s public debt stood at 50.6 percent in 2017, down from 54.2 percent in 2016, according to the statistics office.
Government officials have said that Poland’s general government deficit and debt shrank last year on the back of efforts to ensure spending discipline and a growing stream of tax revenue.
Polish public debt is expected to fall to 38.2 percent of GDP by the end of 2023 under a new strategy adopted by the government last month.
Poland's government in September approved a balanced budget for 2020 that expects the economy to grow 3.7 percent, with inflation targeted at 2.5 percent.
The International Monetary Fund this month revised upward its forecast for Poland’s economic growth in 2019.
In its latest World Economic Outlook report, the IMF predicts Polish GDP will grow 4 percent in 2019, one of the fastest rates of expansion in Europe.
Poland’s central bank chief, Adam Glapiński, said at the start of October that the Polish economy was in "excellent" shape and on track to grow 4.3 percent in 2019.
The Polish economy grew 4.5 percent in the second quarter of this year, the country’s Central Statistical Office (GUS) said in August in a final estimate.