NK Zagreb were the defending champions, having won their first championship title the previous season.
The league format was changed from the previous 2001–02 season and the number of teams were reduced from sixteen to twelve for the 2002–03 Prva HNL.
Because of this, the four bottom-placed teams were automatically relegated to Croatian Second Football League at the end of the season, while the 11th placed Šibenik and 12th placed Kamen Ingrad qualified for the Relegation play-offs.
Both clubs then went on to win the two-legged play-off ties against second level sides Vukovar '91 and Istra Pula.
Therefore, no team was promoted from the 2001–02 Croatian Second Football League and all twelve teams which contested the 2002–03 Prva HNL were also top flight members in the previous season.