| From | Cost | Date | To | Cost | Date | ||
| Oakes | M C | Aston Villa | £500,000 | 29 October 1999 | Cardiff City | Free | 07 July 2007 |
| O’Connor | J P | Quarry Bank Rangers | Fee Unknown | 07 December 1923 | Gillingham | Fee Unknown | 01 August 1923 |
| O’Connor | K J A | Juniors | NA | 12 July 2003 | Stockport County | Loan | 23 March 2006 |
| Telford | Released | 01 July 2008 | |||||
| Odofin | H | Barnet | Fee Unknown | 01 August 2016 | Eastleigh | Loan | 15 December 2016 |
| Northampton Town | Free | 09 July 2018 | |||||
| O’Donnell | F J | Aston Villa | Guest | 1941-42 | NA | ||
| Ofosu-Ayeh | P | Eintracht Braunschweig [Ger] | Free | 20 June 2017 | Hansa Rostock [Ger] | Loan | 01 December 2018 |
| Wurzburger K [Aus] | Loan | 31 January 2019 | |||||
| Halmstads BK [Swe] | Released | 22 August 2020 | |||||
| O’Grady | M | Leeds United | £80,000 | 24 September 1969 | Birmingham City | Loan | 17 February 1972 |
| Rotherham United | Fee Unknown | 08 November 1972 | |||||
| O’Hara | G J | Juniors | NA | 12 July 1973 | Hereford United | Released | 19 January 1978 |
| O’Hara | J D | Tottenham Hotspur | Loan | 30 January 2011 | Blackpool | Free | 05 November 2014 |
| Tottenham Hotspur | £5,000,000 | 21 June 2011 | |||||
| Ojinnaka | T | Juniors | NA | 01 July 2023 | |||
| Ojo | O B | Liverpool | Loan | 03 August 2015 | NA | ||
| Okoronkwo | I | Shaktar Donetsk [Ukr] | Free | 08 January 2003 | Terek Grozny [Rus] | Released | 01 June 2004 |
| Oldershaw | W | 03 March 1905 | 04 March 1905 | ||||
| Oldfield | J S | Huddersfield Town | £20,000 | 24 December 1969 | Crewe Alexandra | Loan | 04 November 1971 |
| Bradford City | Fee Unknown | 31 December 1971 | |||||
| Oldroyd | D R | Everton | Free | 21 August 1986 | Chester City | Released | 10 February 1987 |
| Oliphant | D | Juniors | NA | 01 June 1959 | Carlisle United | Fee Unknown | 02 December 1960 |
| Olofinjana | S G | Brann Bergen [Nor] | £1,700,000 | 01 July 2004 | Stoke City | £3,000,000 | 26 July 2008 |
| O’Mahoney | M | Southport | £1,000 | 17 May 1935 | Newport County | Fee Unknown | 16 March 1936 |
| O’Neill | J | Amateur | NP | 10 December 1942 | Unknown | 28 April 1905 | |
| Oniangue | P | Stade Reims [Fra] | £2,000,000 | 16 August 2016 | SC Bastia [Fra] | Loan | 16 January 2017 |
| SCO Angers [Fra] | Loan | 04 January 2018 | |||||
| SM Caen [Fra] | £500,000 | 12 July 2018 | |||||
| Ordish | C S | Chesterfield | Fee Unknown | 01 May 1936 | Reading | Fee Unknown | 12 February 1938 |
| Osborn | S E | Queens Park Rangers | £1,000,000 | 22 December 1995 | Tranmere Rovers | Loan | 22 March 2001 |
| Port Vale | Free | 05 September 2001 | |||||
| O’Shaughnessy | J P D | Burnley | Fee Unknown | 01 July 2019 | Hednesford Town | Loan | 14 January 2022 |
| Bradford City | Loan | 19 August 2022 | |||||
| Macclesfield Town | Released | 29 January 2023 | |||||
| Otosowie | E | Juniors | NA | 01 July 2019 | Bruges [Bel] | £3,600,000 | 20 August 2021 |
| Owen | B E | Colchester United | Fee Unknown | 20 January 1972 | Retired | 01 May 1973 | |
| Owen | H | Apprentice | NA | NA | Liverpool | £800,000 | 25 July 2023 |
| Owen | I L T | Crewe Alexandra | Fee Unknown | 25 April 1899 | Crewe Alexandra | Fee Unknown | 16 July 1900 |
| Owen | I L T | Amateur | NP | 22 July 1943 | 27 April 1905 | ||
| Owen | W | Loughborough Town | Fee Unknown | 24 August 1895 | Everton |
