The 2002-03 Thai Premier League had 10 teams. Two clubs would be relegated and 2 teams promoted from Thailand Division 1 League. The team that finished in 8th position would play in a relegation play-off. The official name of the league at this time was GSM Thai League.
Krung Thai Bank won their first ever Thai Premier League title and their 5th major title at the time.
This was also the first time that two Thai clubs would enter the Champions League. Osotsapa would also take part but would find the going tough and would crash out in embarrassing circumstances in the group stage.