Libertas has been formally added to the register of political parties by the clerk of the Dáil this morning, according to a statement by the party.
The step follows a 21-day period during which objections to the application could be lodged, and means that Libertas may nominate candidates for any domestic election.
The party logo will now appear on European Parliament ballot papers this June, the statement said.
“This is a landmark step for Libertas," party leader Declan Ganley said.
"I am delighted that we have been formally recognised as a political party, and I want to thank our staff, supporters, and members who made this step possible, and also the staff of the Oireachtas who dealt with our application in the most polite and courteous manner imaginable."
Libertas has already erected billboard posters around the country for several of its European election candidates.
A total of 18 political parties are already listed on the Irish register, including the Progressive Democrats which has not been officially wound up yet.
Libertas and businessman Ganley are best known for their oppositiont to the Lisbon Treaty, the defeat of which last year plunged European Union reform into chaos.
Many political parties and Irish commentators have criticised the lack of transparency of the group and how it was funded.