The developer is planning to installed 1.2GW of offshore wind in the Baltic Sea. The environmental permit relates to an initial 600MW project, set to begin construction in 2019, Polenergia said.
The decision on a second 600MW phase is due to be made by the end of 2016.
Polenergia's Baltic Srodkowy III project is set to comprise 120 turbines at a site 23km off northern Poland.
The permit allows Polenergia to begin technical design of the project.
"The issue of the first environmental decision for offshore wind farms in Poland is a critical milestone in the development of these projects," said Polenergia vice president Jacek Glowacki.
"The total capacity of the planned farm is 1,200MW, which is three times higher than the capacity of [our] onshore wind farm projects, which have been suspended due to the distance limitations.
"We expect that this year both of our projects in the Baltic Sea will be issued environmental decisions," he said.
In May, Poland's new government introduced a distance requirement law for onshore projects.
It stipulates that wind farms must now be located at a minimum distance of ten times the turbine's height from houses and natural protected sites, in practice about 1.5-2km, criteria that observers say very few sites will be able to meet.
Polenergia has approximately 245MW of onshore wind capacity in Poland, according to its website.