"It's a political sensation," concluded party leader Rick Falkvinge.
Falkvinge claimed the success signalled a generation shift in Brussels.
"This means that we can start work to secure citizens' rights, something that we have fought for for three and a half years. This is a reminder to the political old guard that if they take money from the pockets of lobbyists then they will lose their jobs," he told news agency TT.
The election result means that Christian Engström from Nacka in Stockholm will take his seat in the EU parliament in the autumn. He proposed several reasons to explain the sensational success of the party.
"We have spoken about issues that interest people, for example personal integrity. We have also raised issues that are actually EU matters. A third reason is that we have a movement of activists with people from across the country helping out."
With the demise of the June List, who lost their parliamentary seats in the election, the challenge for the Pirate Party is now how to ensure that the same does not happen to them.
"The June List's problem was that they had no clear areas in which they could make a telling difference. We have. The first thing that will happen in the the new EU parliament is the third reading of the telecom reform package. That is an issue that is completely ours," Rick Falkvinge said.