Find MPP by name:
| MPP Sort descending | Riding | Party |
|---|---|---|
| O'Connor, Hamilton Parke | Bruce South | Ontario Liberal Party |
| O'Connor, Lawrence | Durham—York | New Democratic Party of Ontario |
| O'Connor, Terrance P. | Oakville | Progressive Conservative Party of Ontario |
| O'Donoghue, Daniel John | Ottawa | Ontario Liberal Party |
| O'Keefe, George O. | Ottawa (2 Seats) | Ontario Liberal Party |
| O'Neil, Hugh Patrick | Quinte | Ontario Liberal Party |
| O'Neill, John | Toronto Southeast — Seat A | Ontario Liberal Party |
| O'Neill, Yvonne | Ottawa—Rideau | Ontario Liberal Party |
| O'Sullivan, John C. | Peterborough East | Conservative Party |
| O'Toole, John | Durham | Progressive Conservative Party of Ontario |
| Oakley, George | Riverdale | Conservative Party |
| Offer, Steven | Mississauga North | Ontario Liberal Party |
| Oke, Leslie Warner | Lambton East | United Farmers of Ontario |
| Olde, Neil Leverne | Middlesex South | Progressive Conservative Party of Ontario |
| Oliver, Adam | Oxford South | Ontario Liberal Party |
| Oliver, Farquhar Robert | Grey South | Ontario Liberal Party |
| Oosterhoff, Hon. Sam | Niagara West—Glanbrook | Progressive Conservative Party of Ontario |
| Orazietti, David | Sault Ste. Marie | Ontario Liberal Party |
| Ostrom, Gilbert Wellington | Hastings West | Conservative Party |
| Ouellette, Jerry J. | Oshawa | Progressive Conservative Party of Ontario |
| Overall, Cyril Arthur Goodwin | Niagara Falls | Co-operative Commonwealth Federation |
| Owen, Bruce | Simcoe Centre | Ontario Liberal Party |
| Owens, Edward William James | Toronto Southeast — Seat B | Conservative Party |
| Owens, Stephen David | Scarborough Centre | New Democratic Party of Ontario |