The 2009 J.League Division 1 season was the 45th season of the top-flight club football in Japan and the 17th season since the establishment of J.League Division 1. The season started on March 7 and ended on December, 5.

A total of eighteen clubs participated in double round-robin format. At the end of the season, top three clubs received automatic qualification to the following years' AFC Champions League. Also starting this season, the bottom three clubs were relegated to J.League Division 2 by default.

Kashima Antlers became the first Japanese club win J.League Division 1 in three straight seasons.

The following eighteen clubs participated in J.League Division 1 during the 2009 season. Of these clubs, Sanfrecce Hiroshima and Montedio Yamagata were newly promoted clubs.

Eighteen clubs will play in double round-robin (home and away) format, a total of 34 games each. A club receives 3 points for a win, 1 point for a tie, and 0 points for a loss. The clubs are ranked by points, and tie breakers are, in the following order:

A draw would be conducted, if necessary. However, if two clubs are tied at the first place, both clubs will be declared as the champions. The bottom three clubs will be relegated to J2 League. The top three clubs will qualify to AFC Champions League in the following year.

Notes:

Updated to games played on December 5, 2009
Source: J. League Division 1
Notes:
^† Team played previous season in J2.