The 58,000-capacity Warsaw stadium was built specially for Euro 2012 at the cost of 2 billion zlotys ($600 million). The site was previously occupied by a disused 100,000-seat Communist-era stadium which was demolished.
The opening of the new stadium — originally planned for last June — had been repeatedly put off because construction experts and firefighters were finding work incomplete or needing improvement, including faulty outside stairs.
Polish rock bands performed during the opening ceremony before 20,000 fans.
Poland, which co-hosts the event with neighbouring Ukraine, will play Greece in the first match of Euro 2012 on June 8.