The service, which started at 6:00 pm, was celebrated by Archbishop Józef Guzdek.
Held in front of the monument to the Warsaw Uprising, the mass was attended by Poland's President Andrzej Duda and Prime Minister Mateusz Morawiecki, Warsaw Mayor Rafał Trzaskowski, Germany's Minister-President of North Rhine-Westphalia Armin Laschet and a group of insurgents, among others.
A mass was held at Krasiński Square in front of the Monument to the Warsaw Uprising on the eve of the 77th anniversary of the Warsaw Uprising, July 31.
Also, on Saturday afternoon, a special meeting of the City Council met at the Royal castle in Warsaw.
The Warsaw Uprising started at 5 pm on August 1, 1944.
The bloody insurgency resulted in the death of as many as 18,000 fighters and up to 180,000 civilians, according to Poland's Institute of National Remembrance.
The insurgency lasted 63 days before being put down by better equipped and more numerous German forces.
The uprising was the largest military operation by any resistance movement in Europe against the continent's Nazi German occupiers during World War II.
At 5 pm on Sunday, many cars and pedestrians in Warsaw will traditionally come to a standstill, and many drivers were expected to blast their horns in a moving minute-long salute to the fallen fighters.