| Competition: | Irish Premier League |
| Season: | 2004–05 |
| Winners: | Glentoran 22nd Irish title |
| Relegated: | Crusaders Omagh Town |
| Continentalcup1: | UEFA Champions League |
| Continentalcup1 Qualifiers: | Glentoran |
| Continentalcup2: | UEFA Cup |
| Continentalcup2 Qualifiers: | Linfield Portadown |
| Continentalcup3: | UEFA Intertoto Cup |
| Continentalcup3 Qualifiers: | Lisburn Distillery |
| Matches: | 240 |
| Prevseason: | 2003–04 |
| Nextseason: | 2005–06 |
The 2004–05 Irish Premier League was the 104th edition of the Irish League, the highest level of league competition in Northern Irish football, and the 2nd edition in its current format (as the Irish Premier League) since its inception in 2003. The league consisted of 16 teams, and Glentoran won the championship.
Omagh Town were relegated after finishing bottom of the table and subsequently dissolved on 7 June 2005 owing to financial problems. Crusaders were relegated after a 3-1 defeat on aggregate to Glenavon in the promotion play-off.[1]
Before the start of the season Newry Town changed name to Newry City following the change in official status of Newry in 2002.[2]
Each team played every other team twice (home and away) for a total of 30 games.
Crusaders, the club that finished in the relegation play-off place, faced Glenavon, the runners-up of the 2004–05 Irish First Division in a two-legged tie for a place in next season's Irish Premier League.
----Glenavon won 3–2 on aggregate and were promoted, Crusaders were relegated.