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).
Eddie Jones has announced his 27-man squad to train in Oxford until Friday March 3 with centre Jonathan Joseph recalled to training after being released back to Bath during England's win over Italy in Round Three of the RBS 6 Nations.
England fly-half George Ford says his side will put a lot of pressure on themselves to improve as they prepare for their Calcutta Cup match with Scotland at Twickenham in Round Four of the RBS 6 Nations.