1998–99 Irish League

The 1998–99 Irish League was the 98th edition of the Irish League, the highest level of league competition in Northern Irish football. The league consisted of 10 teams, and Glentoran won the championship.

Promotion/relegation play-off
Cliftonville, who finished in the relegation play-off place, faced Ards, the 2nd-placed team in the First Division, in a two-legged tie for a place in next season's Irish League Premier Division.

Cliftonville won 5–2 on aggregate