| Competition: | League of Ireland Premier Division |
| Season: | 2005 |
| Winners: | Cork City (2nd title) |
| Continentalcup1: | UEFA Champions League |
| Continentalcup1 Qualifiers: | Cork City |
| Continentalcup2: | UEFA Cup |
| Continentalcup3: | UEFA Intertoto Cup |
| Continentalcup3 Qualifiers: | Shelbourne |
| Continentalcup4: | Setanta Sports Cup |
| Continentalcup4 Qualifiers: | Cork City Derry City Drogheda United Shelbourne |
| League Topscorer: | Jason Byrne 22 |
| Highest Attendance: | 7,000[2] Cork City F.C. 1–0 Derry City F.C. |
| Prevseason: | 2004 |
| Nextseason: | 2006 |
The 2005 League of Ireland Premier Division was the 21st season of the League of Ireland Premier Division. The division was made up of 12 teams. Cork City were champions while Derry City finished as runners-up. This was the first time the title had been won by a club from outside County Dublin since 1996–97.
The regular season began on 16 March and ended on 18 November. Each team played three rounds of games, totalling 33 games each. The season witnessed a decline in the fortunes of one of the League of Ireland's oldest surviving members. In April Shamrock Rovers entered examinership and it was revealed that the club had debts of nearly €3 million. It was also discovered that Rovers were not playing PAYE and PRSI. As a result of these financial irregularities, Rovers were deducted eight points. This ultimately resulted in the club being relegated to the First Division after they lost the relegation/promotion playoff to Dublin City. This was the first time Rovers' senior team had dropped out of the top level of the Republic of Ireland football league system since the club had joined the League of Ireland in 1922–23.[3] [4]
Going into the final month of the league season only goal difference could separate leaders Cork City from second placed Derry City and title would be decided on the final day of the season when the two met at Turner's Cross on 18 November. Derry City went top of the table after Cork City's draw with Shelbourne the previous weekend. All they needed was a point to seal their first league title since 1996–97. Cork City started the better and nearly scored inside thirty seconds when John O'Flynn headed just over the crossbar. They were not to be denied however, and struck the deserved lead goal when O'Flynn headed home from a Roy O'Donovan cross. Cork City dominated the rest of the opening half but it seemed that the second killer goal would just not come. It eventually arrived in the 16th minute of the second half when Denis Behan set up Liam Kearney to score. Derry City never gave up, however, and were close to pulling a goal back but Michael Devine managed to pull off a fine save from a Pat McCourt header. It was to be Cork City's day, though, as they went on to see the match out and clinch their second league title.[5] [6]
Shamrock Rovers who finished eleventh in the Premier Division played off against Dublin City who finished second in the First Division.
Dublin City win 3–2 on aggregate and are promoted to the Premier Division.[7]
The League of Ireland Premier Division clubs' performances in Europe this season meant that the league received a coefficient of 1.833 added to their overall coefficient which now accumulated to 4.331. This gave them a ranking 40th place as shown.
Belarus
Liechtenstein
Albania
Armenia| Player | Club | League goals | Cup goals | Total | |
|---|---|---|---|---|---|
 Jason Byrne | Shelbourne | 22 | 8 | 30 | |
| Mark Farren | Derry City | 18 | 4 | 22 | |
| John O'Flynn | Cork City | 11 | 4 | 15 | |
| Kevin McHugh | Finn Harps | 13 | 1 | 14 | |
 Eamon Zayed | Bray Wanderers | 12 | 0 | 12 | |
| Glen Crowe | Shelbourne | 8 | 4 | 12 |
The prize funds for the season more than quadrupled. The top clubs also got a financial from the Setanta Cup. The following table shows how eircom League prize money was distributed for the season.
| Position | Premier Division | First Division | League Cup | Fair Play | |
|---|---|---|---|---|---|
| 1 | €100,000 | €25,000 | €15,000 | €4,500 x 2 | |
| 2 | €45,000 | €12,500 | €7,500 | €2,000 x 2 | |
| 3 | €25,000 | €7,500 | €2,500 | ||
| 4 | €15,000 | €6,000 | €2,500 | ||
| 5 | €10,000 | €5,000 | |||
| 6 | €7,500 | €5,000 | |||
| 7 | €6,000 | €5,000 | |||
| 8 | €5,000 | €5,000 | |||
| 9 | €5,000 | €5,000 | |||
| 10 | €5,000 | €5,000 | |||
| 11 | €5,000 | ||||
| 12 | €5,000 | ||||
| Totals | €233,500 | €81,000 | €27,500 | €13,000 |
Attendance figures increased this season in relation to previous seasons. The total attendance over all competitions for the season was 520,000 - a 6% increase on the previous season. The highest league attendance of the season came at Turner's Cross for the title decider at the end of the season between Cork City and Derry City. 8,000 spectators were at the game.
The FAI agreed a new TV Rights deal for this season. This deal will run until 2009. The main terms of the agreement are:
TV viewing figures for the season proved to be in excess of 1 million. In the end 44 matches were televised live with the highest viewing figure of 355,000 for the league title decider.