It will be 24-year-old O'Callaghan's first Test start after winning all eight of his previous caps off the bench. He teams up with Munster second-row colleague Paul O'Connell.
Maggs and O'Kelly drop down to replacement duty, and there is no place in the 22 for Munster wing Anthony Horgan, who went on as a second-half substitute in Paris.
Ireland are bidding for a fifth successive victory over Wales.
Ireland team to play Wales in the RBS 6 Nations Championship at Lansdowne Road, Dublin: G Dempsey (Leinster); S Horgan (Leinster), G D'Arcy (Leinster), B O'Driscoll (Leinster, capt), T Howe (Ulster); R O'Gara (Munster), P Stringer (Munster); R Corrigan (Leinster), S Byrne (Leinster), J Hayes (Munster), D O'Callaghan (Munster), P O'Connell (Munster), S Easterby (Llanelli Scarlets), K Gleeson (Leinster), A Foley (Munster).
Replacements: F Sheahan (Munster), S Best (Ulster), M O'Kelly (Leinster), V Costello (Leinster), G Easterby (Rotherham), D Humphreys (Ulster), K Maggs (Bath).
The RBS 6 Nations Championship 2015 was not poised to go down as one of the more "vintage" Championships, though there was great anticipation as the action headed into its final day. What transpired was something that nobody could foresee: "The Greatest Day in Rugby's Greatest Championship."