He has taken the place of Munster lock Donncha O'Callaghan who limped off during the first half of Sunday's 36-15 victory over Wales after straining the medial ligament in his right knee.
O'Callaghan should recover in time for the clash with Italy at Lansdowne Road on March 20, but until then Paul O'Connell and Malcolm O'Kelly will form the second row with Longwell providing cover from the bench.
Otherwise, O'Sullivan has made no further changes to the side which humbled Wales in Dublin last weekend, with skipper Brian O'Driscoll on course to continue his midfield partnership with the in-form Gordon D'Arcy.
The team to face England will be announced next Tuesday.
Forwards: Best, Byrne, Corrigan, Costello, Easterby, Foley, Gleeson, Hayes, Longwell, O'Connell, O'Kelly, Sheahan.
Backs: D'Arcy, Dempsey, Easterby, Horgan, Howe, Humphreys, Maggs, O'Driscoll (captain), O'Gara, Stringer.