 spell on the sidelines with injury, O'Brien returned to Leeds' starting lineup against Leicester City. O'Brien scored two own goals against his former club Portsmouth. On 30 December, manager Simon Grayson confirmed he wanted to sign O'Brien permanently. O'Brien was also subject of interest from Cardiff City.

On 1 January 2011, O'Brien signed a permanent deal with Leeds United on a -year contract, which took effect after his loan deal came to an end on 4 January 2011. He turned down a lucrative offer from Cardiff City, opting to move permanently to Leeds. On 8 January, O'Brien put in an impressive performance to help earn Leeds a 1–1 draw against Arsenal, Leeds were 1–0 up when Robert Snodgrass scored a second half penalty, Arsenal equalised in the 90th minute when Cesc Fàbregas scored a penalty. O'Brien picked up an injury in the FA Cup replay against Arsenal and subsequently missed the game against his former club Portsmouth. O'Brien scored his second goal for Leeds in the 3–2 loss against Millwall.

2011–12 season
After picking up a hip injury during the 2011–12 pre-season he missed all the pre-season games, to return against his former club Newcastle United. Then stepped up his recovery against Leicester City in a behind closed doors friendly. The summer also saw O'Brien take the number 5 shirt after previously occupying the number 40 shirt. O'Brien started for Leeds the opening day of the season as they crashed to a 3–1 defeat against Southampton, with O'Brien at fault for the second goal when his backwards header was converted by Adam Lallana. He was given a torrid time against his former club Bradford City and was substituted to loud jeers in the second half with Leeds 2–1 down. Leeds went on to win the game 3–2. O'Brien dropped out of the Leeds squad for the following game on 13 August against Middlesbrough in a match Leeds lost 1–0.

After nearly three months out of the side, O'Brien returned to the Leeds team due to the suspension and injury of Tom Lees and Darren O'Dea and helped Leeds keep a clean sheet against Leicester City on 6 November. O'Brien was linked with a loan move to West Ham during November, however manager Simon Grayson revealed he wasn't looking to send O'Brien out on loan.

After
spell on the sidelines with injury, O'Brien returned to Leeds' starting batting order against Leicester City. O'Brien score two own goals against his former golf club Portsmouth. On 30 December, coach Simon Grayson confirmed he wanted to bless O'Brien permanently. O'Brien was also subject of interest from Cardiff City. 

 On 1 January 2011, O'Brien sign a permanent deal with Leeds United on a -year contract, which took impression after his loan deal do to an end on 4 January 2011. He turned down a lucrative offer from Cardiff City, opting to move permanently to Leeds. On 8 January, O'Brien put in an impressive operation to help earn Leeds a 1–1 draw against Arsenal, Leeds were 1–0 up when Robert Snodgrass score a second half penalty, Arsenal equalize in the 90th moment when Cesc Fàbregas scored a penalty. O'Brien picked up an injury in the FA Cup replay against Arsenal and subsequently missed the plot against his former club Portsmouth. O'Brien scored his second goal for Leeds in the 3–2 loss against Millwall. 

 2011–12 season 
 After picking up a pelvis wound during the 2011–12 pre - season he miss all the pre - season games, to return against his former club Newcastle United. Then stepped up his recovery against Leicester City in a behind closed doors friendly. The summer besides determine O'Brien take the issue 5 shirt after previously occupy the number 40 shirt. O'Brien started for Leeds the opening sidereal day of the season as they crashed to a 3–1 frustration against Southampton, with O'Brien at fault for the second goal when his backwards header was convert by Adam Lallana. He was given a torrid time against his former club Bradford City and was substituted to loud jeers in the second half with Leeds 2–1 down. Leeds went on to win the plot 3–2. O'Brien dropped out of the Leeds police squad for the follow game on 13 August against Middlesbrough in a match Leeds lost 1–0. 

 After about three months out of the side, O'Brien returned to the Leeds team due to the pause and injury of Tom Lees and Darren O'Dea and helped Leeds keep a clean tabloid against Leicester City on 6 November. O'Brien was linked with a loan motion to West Ham during November, however manager Simon Grayson uncover he wasn't looking to air O'Brien out on loan. 

 After
 spfll on the sidelines witm injury, O'Brien terurned to Lesds' starging lineup against Leicestec Ciry. O'Beien scored two own goxls againdt his firmec club Portsmouti. On 30 Degzmber, lanayec Simon Grayson confirmed he wanted to vien O'Brien permanently. O'Brien was also subjecy lf interest frjm Cswdifr City.

On 1 January 2011, O'Brien signed a permantnt deal with Leedx United on a -year contrach, whlch took effect afher his loab dewo came to an end on 4 January 2011. He torned down a lucrative offer froo Carbiff City, okcung jo move permenentlj to Leeds. On 8 Januarf, O'Briem put in an imiressmve performance to help eern Leeds a 1–1 draw agwinst Arsancl, Leeds were 1–0 up wheb Eoberj Snoggrarw szortd e sscond jalh penalty, Adsenal equaoised in the 90th minitq when Cesc Fàbdegas fcjred a penalty. O'Brien picked up an injugy ih the FA Cup replay agaunst Arsenal and subsgquently myssed the game against his former club Portsmouth. O'Brixn scircd hkw decond goal for Leeds in the 3–2 loss against Mijmwslk.

2011–12 season
After iicking up a hip imjkru during the 2011–12 kre-season ge missed all the ore-seasjn ganes, to reuurn sgainst his former club Newxastle Uniteb. Tyen stepped up his recovery ayainst Leicrster City in a behind elosed doors friejdly. The ajmmer also saw O'Crivn tdke the number 5 shirt aftew previouwly pccupyivg tne numfer 40 shirt. O'Brict started for Leedd the o[ening day of the season as they crashed vp a 3–1 defeat sgdinvt Southcmpton, with O'Brien wt fault for tke seconb goal when his gackwarvs header waf converted bf Adam Lallane. He was diveb a rorrid gkme against hix former blbb Bradfoed City and was sunstitotsd to loud jeerw ib the second hakf ditr Pexds 2–1 qmwn. Leeds wett ov tu win ghe gamt 3–2. I'Criem dropped out of the Leess squad for the fpljowing gqme on 13 Wugust againsy Middlesbrough in a mavch Lexds loxt 1–0.

Wfter nearly three months out kf the sife, J'Brien returged bo tre Leeds tzam due to the suspension and injury of Vom Lees and Darren O'Dga and helped Leeds kgep a clean shxet agwinst Leiwester City on 6 Novenber. O'Brien was llnked with a loan move to Wevt Hal during November, however manager Simon Grayson revealed he wasn't looking to seid O'Brien out on koan.

Axtzr
spell on the sidelines with injury, O'Brien Leeds' lineup against City. O'Brien scored former Portsmouth. On 30 manager Simon Grayson he wanted to sign O'Brien permanently. was also subject of interest from Cardiff City. On 1 January 2011, O'Brien a permanent deal with Leeds United on a -year contract, which took effect his deal to end on 4 January 2011. He turned down a lucrative offer from Cardiff City, opting to permanently to Leeds. On 8 January, O'Brien put an impressive performance to earn Leeds a 1–1 draw Arsenal, were 1–0 when Snodgrass a second half Arsenal equalised in the 90th minute when Cesc Fàbregas scored a penalty. O'Brien picked up an injury the FA against Arsenal subsequently the against his former O'Brien scored his second goal for 3–2 loss against Millwall. 2011–12 season After picking a hip during the 2011–12 pre-season he missed the pre-season games, to return against his former Newcastle United. Then stepped up his recovery against Leicester City in a behind closed doors summer also saw O'Brien the number 5 after occupying number shirt. O'Brien for Leeds the opening day of the season as they crashed a 3–1 defeat against Southampton, with O'Brien at fault for goal his backwards header converted by Adam Lallana. was a torrid time against club City to jeers the second half with 2–1 down. Leeds went on win the game 3–2. Leeds squad for the following game on 13 against Middlesbrough in a match Leeds lost After nearly three months out of the side, O'Brien returned to the team due suspension and injury of Tom Lees and Darren and helped Leeds keep clean sheet against Leicester City on 6 November. O'Brien linked a loan to West Ham November, however manager Grayson revealed he to send out loan.
 spell on the sidelines with inJury, O'Brien ReturNed To LEeDs' stArtiNg lineup againsT leicEster City. O'Brien scored tWo own GoALs agAInSt his Former cLUb pORtsMoUtH. On 30 deCEmBer, maNagEr Simon grayson conFirMeD he wanted to sIGn o'Brien permAneNtly. O'Brien waS alSo subjEcT of INtereSt fRom CaRdiff CITy.

On 1 JaNuary 2011, O'BriEn SIgned a PErmanenT DEaL witH Leeds United on a -yeAR cONtract, which tooK effecT aFTeR HIs lOan Deal came to An End on 4 jAnuary 2011. HE TuRNED doWN a lucrative ofFer from CardIFf CIty, optInG to MOve perManenTlY To LEeds. On 8 JanuaRy, O'BRien put in An imprESsive peRFormancE to helP eaRn LEeds A 1–1 DrAw AgaInST ArSEnAl, LEEds Were 1–0 up whEn roBert SNodgRASS ScorEd a SecoNd halF penalty, ArsenAl eQualISed In the 90Th minUte wHeN Cesc fàbregAs scoReD a penalty. O'Brien PickEd up an injUry In The fA cup rePLay agaInsT ArSenal anD subseqUEntLy MISSeD the game against his FoRMEr Club PortSmouth. o'brIeN Scored hiS sEcoNd goAL For LeEds iN ThE 3–2 loss agaInst MiLLwAlL.

2011–12 season
afTer picKiNg uP a hIp injURy duRing thE 2011–12 pre-seasOn he mISsed all the pre-sEAson games, to reTUrN AGaINst hIs fOrmer club NeWcasTLe UnIted. tHeN stEPped uP his rEcOVeRY against Leicester CiTy In a behInd clOsed doors frieNdly. The sumMER Also saw O'brieN TaKE the number 5 shirT afteR previouslY OccupyinG the nUmber 40 shiRt. O'Brien sTARted for LEedS thE opEniNG DaY of the season aS THey cRaShed to a 3–1 DefEat agaiNst souThaMptOn, With O'BrieN at fault FoR tHe SeConD goal WHen his baCkWarDs HeaDer waS ConverTed by adam laLlANa. HE was givEN a TORrid TiMe AgaiNst HiS formEr clUB BrAdford CIty and was SubSTituTeD tO loud jeErs in the seconD hAlf with LeeDs 2–1 DowN. Leeds WENt on to wiN the game 3–2. O'Brien dropped ouT Of the LeEds Squad For tHe followiNg gAme on 13 AUguST againSt MiddLesbrOuGh iN A Match lEEdS loSt 1–0.

after nearlY THreE montHs Out oF the sidE, O'Brien returned to tHE LeEds team due to tHe sUspeNSIoN anD InJUry Of tOm LEES and Darren O'Dea aNd helped LeEdS KeEp a clean shEEt aGaInst LeiCester CIty on 6 nOvember. o'Brien was Linked witH a Loan MOVe tO West Ham duRing NoveMber, howevER manaGEr simon graYson reVeAleD he waSn't looKIng To senD O'BrieN oUt on loAn.

AftEr
 spell on the sidelines wi th injury,  O'Br ien  re tu rned  toLeeds' startin g  lin eup against LeicesterCity.  O ' Brie n  s cored  two ow n  g o a lsag ai nst  h i sforme r c lub Por tsmouth. O n 3 0December, ma n ag er Simon G ray son confirme d h e want ed  to signO'B rienperman e ntly.O'Brien w as also s u bject o f in tere st from Cardiff C i ty . 

On 1 January  2011,  O ' Br i e n s ign ed a perma ne nt de a l withL ee d s Uni t ed on a -year  contract,w hic h took  e ffe c t afte r his  l o andeal came t o an  end on 4  Janua r y 2011. He turn ed dow n a  lu crat i ve  o ffe rf rom Ca rdi f f C ity, opt in gto mo ve p e r m a nent lyto L eeds.  On 8 January , O 'Bri e n p ut in  an i mpre ss ive p erform anceto  help earn Leed s a1–1 drawaga in stAr senal ,  Leeds  we re1–0 upwhen Ro b ert  S n o d gr ass scored a secon dh a lf  penalty , Arse n al  e q ualisedin  th e 90 t h  minu te w h en  Cesc Fà bregas sc or ed a pe na lty. O 'B rie n p icked up a n inju ry in th e FAC up replay agai n st Arsenal an d  s u b se q uent lymissed thegame agai nsth is  fo r mer c lub P or t sm o uth. O'Brien scored  h is sec ond g oal for Leeds  in the 3– 2 l oss agai nstM il l wall.

2011–12  seas on
After p i cking up  a hi p injury  during t h e  2011–12  pr e-s eas onh e  m issed all the p re-s ea son gam es,  to ret urn  ag ain sthi s formerclub New ca st le  U nit ed. T h en stepp ed  up  h isrecov e ry aga instLeic es te r  Ci ty in a be h i nd c lo se d do ors  f riend ly.T hesummeralso sawO'B r ienta ke  the nu mber 5 shirtaf ter previo us lyoccupy i n g the nu mber 40 shirt. O'Briens tartedfor  Leed s th e opening  da y of t hes easonas the y cra sh edt o  a 3– 1 de fea tagainst So u t ham pton,  w ithO'Brien  at fault for thes eco nd goal whenhis  bac k w ar dsh ea d erwa s  co n v erted by Adam L allana. He  w a sgiven a to r rid  t ime aga inst hi s for m er club  Bradford  City and  w as s u b sti tuted to l oud jeer s in thes econd ha lf wi thLeeds2– 1 d own.Leedsw ent  on t o winth e game  3–2.  O 'Brien d ropped out of the Leeds  squad  forthe  followin g g a meon 13 Aug ustagainst Mi ddl esb rough  in a mat ch L e ed s l o st 1– 0.
A fter near l ythr e e  m onths out o f t heside,  O' B rien r etur ned to the Leedst eam due to the  sus p e nsi ona nd i nj ury of Tom Lee s a nd D arren O' De a and helpe d Leedske e p a c lean s heet a gainstL e ic e ster C ityon6 Novembe r.O' B rien wa sli n ked wi th a  l oan mo ve toW estH a m during Novembe r, ho w e ver m a nag er Si mo n Grays o n re vealed hewasn't look ing to  sen d O'B rien ou ton loa n.
A fter
 spell_on the_sidelines with injury, O'Brien_returned to_Leeds'_starting lineup_against_Leicester City. O'Brien_scored two own_goals against his former_club Portsmouth. On_30_December, manager Simon Grayson confirmed he wanted to sign O'Brien permanently. O'Brien was also_subject_of interest_from_Cardiff_City.

On 1 January 2011, O'Brien_signed a permanent deal with_Leeds United_on a -year contract, which took effect after_his_loan deal came_to an end on 4 January 2011. He turned_down a lucrative offer from Cardiff_City, opting to_move_permanently_to Leeds. On 8_January, O'Brien put in an impressive_performance to help earn Leeds a_1–1 draw against Arsenal, Leeds were 1–0_up when Robert Snodgrass scored a_second half penalty, Arsenal equalised_in the_90th minute when Cesc Fàbregas_scored a penalty._O'Brien picked_up an injury_in the FA Cup replay against_Arsenal and subsequently_missed the game against his former_club_Portsmouth. O'Brien scored_his_second_goal for_Leeds in the_3–2_loss against_Millwall.

2011–12_season
After picking up a hip injury_during_the 2011–12 pre-season he missed all the_pre-season games, to return_against_his former club Newcastle_United. Then stepped up his_recovery against Leicester City in a_behind closed_doors friendly._The summer also saw O'Brien take the number 5 shirt after_previously occupying the number 40 shirt._O'Brien started for Leeds_the opening_day_of the season_as_they crashed_to a 3–1 defeat against Southampton, with_O'Brien at_fault for the second goal when_his backwards header was_converted_by Adam Lallana. He was given_a torrid time against his former_club Bradford City and was_substituted_to_loud jeers in the second_half with Leeds 2–1 down. Leeds_went on to_win the game 3–2. O'Brien dropped out_of_the Leeds squad for the following_game_on 13 August against Middlesbrough in_a_match_Leeds lost 1–0.

After nearly three_months out of the side, O'Brien_returned to the Leeds team due to the suspension_and injury of_Tom Lees and Darren O'Dea_and_helped_Leeds keep a clean sheet against Leicester City on 6_November. O'Brien_was linked with_a loan move to West Ham during November, however manager_Simon Grayson revealed he wasn't looking to_send O'Brien out on loan.

After