or
Player positions provided by the CFL and errors are known to exist
| Name | Position | Regular GP | # of Seasons (Years) | Also played for |
|---|---|---|---|---|
| O'Billovich, Jack | LB | 1 | 1 (1967) | |
| O'Breza, Bill | C, T | 33 | 4 (1946–1949) | |
| O'Brien, John | LB | 3 | 1 (1990) | |
| O'Brien, Mike | P | 1 | 1 (2002) | SSK |
| Ochiena, Ed | E | 9 | 1 (1962) | TOR |
| O'Connor, Okey | E | 4 | 1 (1945) | |
| Odegard, Don | DB | 15 | 1 (1994) | MPH, TOR |
| Odiase, Osagie | DB | 7 | 1 (2017) | CGY |
| Ojuri, Sam | RB | 1 | 1 (2014) | |
| Okafor, Kay | OL | 27 | 2 (2018–2019) | |
| Olive, Bobby Jr. | WR | 16 | 1 (1998) | |
| Oliver, Bobby Jack | K, T | 2 | 1 (1964) | EDM, MTL, TOR |
| Ollinger, Jerry | HB, QB | 5 | 2 (1945–1946) | |
| Ollman, Tommy | HB | 2 | 1 (1948) | |
| Olson, Jake | LT, OL | 21 | 3 (2014–2016) | |
| Omara, Ron | DL, LB | 25 | 2 (2015–2016) | BC, OTT |
| O'Neal, Calvin | LB | 1 | 1 (1979) | |
| O'Neal, Jesse | DL | 8 | 1 (1979) | BC, SSK |
| O'Neill, Hugh | K, P | 8 | 1 (2015) | BC, EDM |
| O'Neill, Tim | C, LG, OL, RG | 72 | 4 (2012–2015) | BC, CGY |
| Oneschuk, Steve | HB, K | 60 | 6 (1955–1960) | |
| Onions, Len | E, FW, HB | 11 | 3 (1938–1940) | |
| Orange, Doyle | RB | 8 | 1 (1977) | TOR |
| Oriard, Mike | T | 6 | 1 (1974) | |
| Ortiz, Sean | DL | 4 | 1 (2011) | BC, MTL |
| Osbaldiston, Paul | K, P | 296 | 18 (1986–2003) | BC, WPG |
| O'Shea, Mike | LB | 66 | 4 (1993–1995, 2000) | TOR |
| Overton, Bill | DB | 3 | 1 (1969) | |
| Owens, Chad | SB | 12 | 1 (2016) | MTL, SSK, TOR |
| Ozarko, Mike | T | 18 | 3 (1938–1940) | OTT, OTTC |
| “O” player count: 30 | ||||