| Irish Cup | |
| Year: | 1988–89 |
| Num Teams: | 76 |
| Defending Champions: | Glentoran |
| Second: | Larne |
| Matches: | 81 |
| Goals: | 263 |
| Prev Season: | 1987–88 |
| Next Season: | 1989–90 |
The 1988–89 Irish Cup was the 109th edition of the Irish Cup, Northern Ireland's premier football knock-out cup competition. It concluded on 6 May 1989 with the final.
Glentoran were the defending champions after winning their fourth consecutive Irish Cup the previous season by beating Glenavon 1–0 in the 1988 final.[1] Their grip on the cup was finally broken by Linfield, who defeated them in the quarter-finals to inflict Glentoran's first Irish Cup defeat in 5 years. Ballymena United won the cup for the fifth time (sixth if you include Ballymena's record), defeating Larne 1–0 in the final.[2] To date, this is Ballymena United's last cup success. In fact, they did not reach the final again until 2014.
The cup was expanded to 76 clubs this season, including more non-league clubs. There would now be five rounds, then the quarter-finals, semi-finals and the final.
Annalong Swifts, Downshire Young Men, RUC, Queen's University and Blue Circle all received byes into the second round.
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The 14 top flight clubs entered in this round, along with the seven third round winners, and 11 non-league clubs given byes to this round.
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