The 2009–10 Croatian First Football League (officially known as the T-Com Prva HNL for sponsorship reasons) was the nineteenth season of the Croatian First Football League, the national championship for men's association football teams in Croatia, since its establishment in 1992. It began on 24 July 2009 and ended on 13 May 2010. Dinamo Zagreb were the defending champions, having won their eleventh championship title (and fourth consecutive title) the previous season, and they defended the title again, after a goalless draw with Hajduk Split on 1 May 2010.
The format was changed from previous season in that the league was expanded from 12 to 16 clubs.
Promotion and relegation from 2008–09
Due to the expansion, no teams were directly relegated following the 2008–09 season.
Four teams from 2008–09 Druga HNL earned direct promotion. These were champions Istra 1961, runners-up Karlovac, third-placed Lokomotiva and fifth-placed Međimurje. Fourth-placed team Slavonac CO had to step back from promotion after they were not able to find a suitable ground.
Croatia Sesvete as last-placed team had to compete in a two-legged play-off against the sixth-placed team from Druga HNL, Hrvatski Dragovoljac. After a scoreless first leg, Croatia Sesvete retained their Prva HNL status by winning the second leg, 2–1.
Overview
Teams
Stadia and locations
Since most Druga HNL stadiums failed to meet the licensing requirements for top-level football, the Croatian Football Federation announced on 8 May 2008 that clubs who are likely to win promotion berths have agreed to lease stadiums approved for top-flight football. Below is the list of all the stadiums which are licensed to be used in the Prva HNL, along with their home clubs and the promoted clubs who secured rights to use them as "guests" until their own grounds have sufficiently been upgraded to host top-level matches.