The tariff cuts, which complete a European Union ruling from 2007, were proposed by the EU's executive arm at the end of 2008 and won approval by the European Parliament and member states.
Following the new price curbs, which take effect on July 1, it will be up to 60 percent cheaper to send mobile phone text messages while traveling in the EU or to surf the Web by laptop.
All Europeans making calls or sending texts with their mobiles can experience the EU's single market without borders. The roaming rip-off is now coming to an end, EU Telecoms Commissioner Viviane Reding said in a statement.
Operators will be allowed to charge customers a maximum of 11 euro cents (15 U.S. cents) per roamed text message (SMS), excluding sales tax, compared with current prices of about 28 cents.
As of July 1, prices for making a roamed mobile call will be capped at 43 euro cents per minute versus 46 cents previously, and at 19 cents, down from 22 cents, for calls received abroad.
The caps will further fall to 39 cents for calls made and 15 cents for calls received while roaming from July 1, 2010 and to 35 cents and 11 cents from July 1, 2011.
Downloading data while roaming will cost a maximum of 1 euro per megabyte from Wednesday at the wholesale level compared with about 1.68 euros today.
Operators must also introduce per-second billing after 30 seconds for roamed calls made and from the first second for calls received abroad.
Until now, consumers paid up to 24 percent more than the time actually used making or receiving calls.
The European Commission wants to end bill shock, when business travelers or holidaymakers return home to huge charges for checking emails or surfing the Web while away by introducing a cut-off mechanism once the bill reaches 50 euros.
The GSM Association, which represents major mobile operators, has said the latest measures -- when they were introduced -- were unnecessary and that data prices were already falling.
(Writing by Bate Felix and Pete Harrison; Editing by Dale Hudson)