The president’s signature came after Polish lawmakers definitively approved the financial plan in a final vote earlier this month.
The budget deficit is expected to be no more than PLN 82.3 billion (around EUR 18.2 billion, USD 22 billion) this year, under the plan greenlighted by the head of state.
Government revenue is expected to total PLN 404.4 billion in 2021, with spending set at PLN 486.7 billion.
Finance Minister Tadeusz Kościński said last year that the 2021 budget would be "another stage in the plan to get back on the path of growth after the global COVID-19 lockdown."
The proposed budget ensures full financing for the government’s key social assistance projects, including its flagship "500-plus" child benefit programme and subsidised school supplies for children nationwide, officials have said.
Meanwhile, health spending is expected to increase to 5.3 percent of GDP, and defence spending is expected to grow to 2.2 percent of GDP.
Poland's unemployment rate is projected to rise to 7.5 percent at the end of this year, from 6.2 percent at the end of 2020.
Amid the coronavirus pandemic, Poland's parliament in October approved plans to revise Poland’s 2020 budget, with the deficit in 2020 expected to reach PLN 109.3 billion (EUR 24.1 billion, USD 29.2 billion).
Poland’s lawmakers in July voted 237 to 212, with no abstentions, to approve the government’s handling of the country’s 2019 budget.
Poland finished 2019 with a budget deficit of PLN 13.7 billion (around EUR 3 billion, USD 3.7 billion), roughly half of the original PLN 28.5 billion target, according to a government report.
Government revenue totaled PLN 400.5 billion in 2019, while spending stood at PLN 414.3 billion, according to the report approved by the lower house of parliament on July 24.
According to the state-run Central Statistical Office (GUS), the Polish economy contracted 1.5 percent in the third quarter of last year, after shrinking 8.4 percent in the second quarter amid the coronavirus crisis.