| Oakeley | Rachel | Victoria | E | Bowen Buchbinder Vilensky | 02/02/2007 | |
| Oakley | Brenton | Leonard | E | Wojtowicz Kelly | 02/02/1995 | |
| O'Brien | Rebecca | | E | Hotchkin Hanly | 03/03/2004 | |
| O'Brien | Rebekah | Kate Farr | E | Jackson McDonald | 04/09/2001 | |
| O'Brien | Richard | John | EP | O'Sullivan Davies | 23/12/1983 | |
| O'Brien | Simon | Patrick | S | Patrick Legal | 02/10/2003 | |
| O'Brien | Susan | Elizabeth | SG | Legislative Council Committee Office | 02/02/1990 | |
| O'Brien | Victoria | Sue Yen | E | Legal Aid of Western Australia | 20/07/2005 | |
| O'Byrne | Anna | June | E | Hardy Bowen | 21/01/2010 | |
| O'Callaghan | Luke | Patrick | E | Jackson McDonald | | |
| O'Connell | Maureen | Bijou | E | Nigam, SC & Co | 18/12/2009 | |
| O'Connor | Anna | Elizabeth | E | Legal Aid of Western Australia | 02/02/2007 | |
| O'Connor | Jacinta | | E | Shine Lawyers | 02/02/2007 | |
| O'Connor | John | Anthony | S | O'Connor Lawyers | 03/04/1990 | |
| O'Connor | Louise | De Marillac | SG | Office of the Director of Public Prosecutions (State) | 02/02/1988 | |
| O'Connor | Michael | Patrick | DI | O'Connor Partners | 23/12/1975 | |
| O'Connor | Robert | Kenneth | B | O'Connor, RK, QC | 15/02/1977 | QC |
| O'Dea | John | Benedict | NP | Not Practising | 03/08/2010 | |
| O'Dell | Malcolm | | E | Central Desert Native Title Services | 02/05/2000 | |
| O'Donnell | Erin | Louise | SG | Office of the Director of Public Prosecutions (State) | 04/02/2003 | |
| O'Donnell | Jamie | | E | Jackson McDonald | 19/12/1997 | |
| O'Donovan | James | | E | Lavan Legal | 20/12/1985 | |
| Odorisio | Nino | Anthony | EP | Q Legal | 14/07/1995 | |
| O'dwyer | Lee | Alison | SG | Parliamentary Counsel's Office | 15/02/1983 | |
| Offer | Rachael | Elizabeth | SG | Landgate | 04/02/1992 | |
| Offer | Thomas | Henry | B | Offer, TH | 03/04/1990 | |
| Offerman | Steven | | E | Friedman Lurie Singh & D'Angelo | 21/01/2008 | |
| Ogden | Raija | Mirjami | E | Lawfield, Legal Practice | 05/03/2002 | |
| Ogilvie | Jamie | George Michael | E | McKenzie Moncrieff Lawyers | | |
| O'Halloran | Jeffrey | William | SG | Office of the State Solicitor | 23/12/1982 | |
| O'Halloran | Joseph | Frederick | S | O'Halloran, JF | 21/12/1962 | |
| O'Halloran | Paul | John | S | O'Halloran, PJ | 23/12/1980 | |
| O'Hanlon Creed | Nicholas | Philip | EP | Mallesons Stephen Jaques | 04/11/2003 | |
| O'Hara | Brendan | Wayne | I | Paladin Energy Limited | 22/12/1989 | |
| O'Hara | Hayley | Evelyn | E | Aboriginal Legal Service of Western Australia (Inc) | 18/12/2009 | |
| O'Hara | Jessica | Louise | E | Allen & Overy | 03/03/2004 | |
| O'hare | Helena | | SG | Parliamentary Counsel's Office | 04/02/1985 | |
| O'Hurley | Anthony | Joseph | EP | Gibson & Gibson | 02/03/1988 | |
| O'Kane | Michael | Benjamin | E | Mallesons Stephen Jaques | 18/12/2009 | |
| Okeby | Donald | Mark | I | Regis Resources | 01/09/1980 | |
| O'Keeffe | Kylie | Marie | FP | Lavan Legal | 02/02/2006 | |
| O'Keeffe | Richard | Simon | NP | Not Practising | 05/09/2008 | |
| Old | Corinne | Louise | SG | Water Corporation | 05/02/2004 | |
| Oldfield | Nova | Natalie | DI | Oldfield Legal | 14/07/1995 | |
| O'Leary | Cassandra | Tatum | E | Jackson McDonald | 05/03/2009 | |
| O'Leary | Matthew | Peter | E | Freehills | 05/03/2009 | |
| O'Leary | Timothy | Paul | E | Blakiston & Crabb | 02/03/2001 | |
| Oliveira | Tonia | Paola | I | ASX Ltd | 02/03/2007 | |
| Oliveiro | Jean | Millicent | E | HFM Legal | 02/10/1981 | |
| Oliver | David | Franklin | SG | Department for Child Protection | 02/03/1994 | |
| Olivier | John | Paul Testaferrata | DI | Talbot Olivier | 22/12/1964 | |
| O'Malley | Amber | Jane | I | Capricorn Society Limited | 11/05/2009 | |
| Ong | Lester | Eng Seong | E | Munro Doig | 17/07/2002 | |
| Ong | Valerie | Pui Yee | E | Freehills | 04/04/2006 | |
| Ong | Yee | Yang | E | Downings Legal | 12/07/2000 | |
| Onofaro | Tanya | Rachel | E | Lavan Legal | 04/03/2010 | |
| Oprandi | Emilia | | E | James Chong Lawyers | 23/12/1994 | |
| Orman | Mitchell | | E | Mendelawitz Morton | 04/02/2003 | |
| O'Rourke | Katie | Jane | E | Kimberley Land Council | | |
| O'Rourke | Megan | Mary | EP | Corrs Chambers Westgarth | 04/11/2003 | |
| Osborn | Catherine | Louise | FP | Marks and Sands | 02/08/2002 | |
| Osborn | Christopher | John | E | Williams & Hughes | 04/08/1992 | |
| Osborn | Debra | Jean | E | Blake Dawson | 02/05/2003 | |
| Osborne | Heather | Jessica | E | Jackson McDonald | 21/12/2000 | |
| Osborne | Terence | Anthony | E | Northern Suburbs Community Legal Centre Inc | 03/02/1998 | |
| O'Shannassy | Richard | John | DI | Richard O'Shannassy & Co Pty Ltd | 21/12/1979 | |
| O'Shannessy | Gregory | John | E | Murcia Pestell Hillard | | |
| Osmanhodzic | Amy | Marie | E | Minter Ellison | 05/03/2009 | |
| Osmani | Mariem | | A | Australian Taxation Office | 02/08/2005 | |
| O'Sullivan | Bronwen | Joy | S | Lane Buck & Higgins | 23/12/1993 | |
| O'Sullivan | Colin | Peter | EP | O'Sullivan Partners | 22/12/1978 | |
| O'Sullivan | Elizabeth | Jane Louise | C | Leach Legal | 02/03/1994 | |
| O'Sullivan | Hugh | Mark | SP | SRB Legal | 03/02/1987 | |
| O'Sullivan | John | Francis | SG | Office of the State Solicitor | 02/03/1994 | |
| O'Sullivan | John | Lawrence Scott | DI | O'Sullivan Law | 20/12/1991 | |
| O'Sullivan | Kevin | David Paul | EP | Clayton Utz | 21/12/1984 | |
| O'sullivan | Matthew | John | SG | Office of the Director of Public Prosecutions (State) | 02/11/2005 | |
| O'Sullivan | Sean | Walter | B | O'Sullivan, SW | 23/12/1966 | |
| O'Sullivan | Trevor | George | EP | O'Sullivan Davies | 21/03/1972 | |
| Oteri | Maurizio | Antonio | E | Robertson Hayles Lawyers Pty Ltd | 11/02/2008 | |
| O'Toole | Barry | John | S | O'Toole & Co | 02/04/1985 | |
| O'Toole | Conal | Patrick | S | Conal O'Toole Lawyer | 05/06/1985 | |
| O'Toole | Kevin | James | E | University of Western Australia | 03/02/1987 | |
| O'Toole | Mark | Torsten | E | Minter Ellison | 18/12/2009 | |
| Ottolini | Franca | | E | Northern Suburbs Community Legal Centre Inc | 03/09/2009 | |
| Oud | Nicholas | Neil Peter | E | Brett Davies Lawyers | 02/03/1995 | |
| Overmars | Johanna | Lillian | E | Kott Gunning | 04/10/2005 | |
| Owen | Brett | Leslie | E | LHMU Legal | 04/03/2010 | |
| Owen | Christian | John | SP | Corrs Chambers Westgarth | 22/12/1999 | |
| Owen | Emma | Celeste | SG | Office of the State Solicitor | 02/03/2001 | |
| Owen | Geoffrey | | EP | McLeods | 23/12/1992 | |
| Owen | Melissa | Marie | E | Johnson Winter & Slattery | 02/04/2008 | |
| Owen | Rebecca | Lian | SG | Office of the State Solicitor | 02/02/2000 | |
| Owen | Robert | Francis | E | Aboriginal Legal Service of Western Australia (Inc) | 19/12/2008 | |
| Owen | Simon | Llewellyn | E | Gadens Lawyers | 22/12/1989 | |
| Owen-Conway | Natasha | | B | Owen-Conway, N | 18/12/1987 | |
| Owen-Conway | Stephen | | B | Owen-Conway, S, QC | 10/11/1977 | QC |
| Owens | Maxwell | Charles | S | Owens, M & Co | 22/12/1978 | |
| Ozcan | Muge | | E | Key Legal Pty Ltd | 01/11/2007 | |