The team with the most points at the end of the season crowned champions.
Evagoras Paphos and Ethnikos Achna were relegated from previous season and played in the 1990–91 Cypriot Second Division.
They were replaced by the first two teams of the 1989–90 Cypriot Second Division, EPA Larnaca and APEP.
The 12th-placed team Enosis Neon Paralimni faced the 3rd-placed team of the 1990–91 Cypriot Second Division Ethnikos Achna, in a two-legged play-off for one spot in the 1991–92 Cypriot First Division.
Enosis Neon Paralimni won both matches and secured their place in the 1991–92 Cypriot First Division.