[3] On 5 October, Dundalk won the title after a 1–1 draw with St Patrick's Athletic.
Waterford, the 2017 First Division champion, were promoted to the league for the first time since 2007.
On 22 December 2016, the Football Association of Ireland announced that the league would be restructured into two 10-team divisions from the 2018 season onwards, one of the recommendations made in the 2015 Conroy Report.
[6] Note: Flags indicate national team as has been defined under FIFA eligibility rules.
Finn Harps won 3–0 on aggregate and were promoted to 2019 Premier Division.