The season began on 4 August 2018 and concluded on 27 April 2019, with the play-offs for promotion/relegation and the Europa League then taking place in May 2019.
Newry City finished bottom of the table, and were relegated to the 2019–20 NIFL Championship after only one season in the top flight.
Eleventh-placed Ards faced 2018–19 NIFL Championship runners-up, Carrick Rangers, in a two-legged promotion/relegation play-off.
This brought an end to Ards' three-season stay in the top flight, and meant an immediate return to the Premiership for Carrick Rangers after only one season in the Championship.
[3] Premiership champions Linfield entered the 2019–20 UEFA Champions League, with the runners-up (Ballymena United) and the play-off winners (Cliftonville) entering the 2019–20 UEFA Europa League along with the 2018–19 Irish Cup winners, Crusaders.
Carrick Rangers won the tie 3–1 on aggregate to secure promotion to the 2019–20 NIFL Premiership, with Ards being relegated to the Championship.