Tuhia he tomokanga mō tēnei wāhanga - I muri i tana tohu i te whare wānanga o Connacht, i hainatia a O'Halloran ki tētahi kirimana whanaketanga mō te tau 2011<unk>12. I taua wa ka eke a Connacht ki te Heineken Cup, te whakataetae karapu nui o Europi, mo te wa tuatahi. I te 11 Whiringa-a-rangi 2011, i eke a O'Halloran ki te whakamatau tuatahi a Connacht i te whakataetae ki a Harlequins i te rauna whakatuwhera. I whakaatuhia hoki ia mo Connacht i te hinganga 36-10 ki a Toulouse i te 2009 me te hinganga 23-19 ki a Gloucester, ka eke ki tetahi atu whakamatautau ki a Gloucester. I takaro a O'Halloran i te hinganga 24-3 ki a Toulouse engari i takaro i te wikitoria Heineken Cup tuatahi o te kawanatanga i te wa i wikitoria ai a Connacht i a Harlequins 9-8. I te 2011<unk>12 Pro12
I eke a O'Halloran i nga whakataetae e rua ki te Cardiff Blues me nga whakamatautau a Leinster me Glasgow Warriors. I roto i te Rauna 20 o nga whakataetae, i eke a O'Halloran ki te whakamatau i te wikitoria 26 <unk> 21 i runga i a Ulster ki te kawe i ana whakamatautau ki te rima i te Pro12 me te whitu i nga whakataetae katoa.