The Credit Institutions Financial Support Bill has been signed into law.
President Mary McAleese signed the document this afternoon at Áras an Uachtaráin.
The legislation to guarantee deposits in Irish banks was debated for over 24 hours in the Dáil and Seanad, and will come into immediate effect.
Labour was the only political party to vote against the legislation.
The party raised concerns about the level of power being given to the Finance Minister and a need for better regulation of the banking sector.