Murphy has been included after Felix Jones was ruled out with an ankle injury sustained in Saturday's match against France.
Murray is selected at the expense of provincial team-mate Tomas O'Leary.
Lions winger Luke Fitzgerald, who would have been seen as an automatic selection a year ago, has missed out.
Limerick man Murray, who made his only Test appearance against France in Bordeaux nine days ago, travels with fellow scrum-halves Eoin Reddan and Isaac Boss.
O'Leary was thought to be coach Declan Kidney's first choice in the position but has paid the price for his poor display in Saturday's 26-22 defeat by the French in Dublin.Luke Fitzgerald has been left out of Ireland's squad
Murphy's hopes of inclusion looked slim until the Jones injury narrowed the options of Kidney who chose the 33-year-old as cover for first choice full-back Rob Kearney.
Four years ago Murphy made one appearance at the World Cup in France, while in 2003 he missed out after breaking his leg on the eve of the squad announcement.
"Geordan - isn't that a real case of the highs and lows of sport?" said Kidney.
"I was involved eight years ago when Geordan broke his leg in Edinburgh. Now he gets his opportunity here too.
"He is an experienced man and brings a lot off the pitch as well as on it.
"We went through a situation in the Six Nations when Geordan, Rob and Felix were all injured. Two of the three are fit now.
"It is a specialist position and you need to know what you are doing, especially at this level."Ireland coach Declan Kidney names his 30 man squad for the 2011 Rugby World Cup
Alongside O'Leary, Fitzgerald is another big-name casualty who has also suffered because of a loss of form.
Fitzgerald played well as a second-half substitute against France in Dublin, but it was not enough to convince Kidney he should travel.
Most of the squad of 16 forwards and 14 backs picked itself.
Only four props will travel, with Tony Buckley securing the last available place, beating off competition from John Hayes and Marcus Horan.
Donnacha Ryan travels as the fourth lock but also offers back row cover, while Stephen Ferris features after making his first appearance since January on Saturday.
Andrew Trimble's fine form during the summer is rewarded and his rival wing Tommy Bowe is present despite not having played this month because of a foot injury.
Ireland squad: R Best (Ulster), I Boss (Leinster), T Bowe (Ospreys), T Buckley (Sale), T Court (Ulster), S Cronin (Leinster), L Cullen (Leinster), G D'Arcy (Leinster), K Earls (Munster), S Ferris (Ulster), J Flannery (Munster), C Healy (Leinster), J Heaslip (Leinster), R Kearney (Leinster), D Leamy (Munster), F McFadden (Leinster), G Murphy (Leicester), C Murray (Munster), S O'Brien (Leinster), D O'Callaghan (Munster), P O'Connell (Munster), B O'Driscoll (Leinster, capt), R O'Gara (Munster), E Reddan (Leinster), M Ross (Leinster), D Ryan (Munster), J Sexton (Leinster), A Trimble (Ulster), P Wallace (Ulster), D Wallace (Munster).