A midnight ceremony will be held at nearby Westerplatte, where the first shots of the war were fired.
As the world marks the 70th remembrance of World War II, the Polish port of Gdansk is set to play host to European leaders.
BBC reports that a midnight ceremony will be held at nearby Westerplatte, where the first shots of the war were fired.
Expected at the remembrance ceremony are presidents of several countries including Bulgaria, Czech Republic, Estonia, Lithuania, Romania and Ukraine.
Also, France is to send Defence Minister Jean-Yves Le Drian and Germany will send former president Horst Koehler.
While the anniversary will be marked by other events around the world over the weekend, a military parade in Moscow on Saturday is being boycotted by most Western countries owing to the soured relations between the West and Russia over the latter's annexation of Crimea last year and support for rebels in eastern Ukraine.
In an interview with a Polish publication, Polish President Bronislaw Komorowski said the end of World War II did not bring freedom to eastern Europe because states were "subordinated against their will" by the Soviet Union.
Nazi Germany invaded Poland on 1 September 1939, shelling a Polish garrison at Gdansk. 2 days later, the UK and France declared war on Germany.