Kongdej graduated from the film department at King Mongkut's Institute of Technology Ladkrabang. He began his career in the late 1990s directing music videos for the record label RS Promotion. He also wrote screenplays for the company's then new RS Film, but none were ever produced.[1]
Kongdej made his directorial debut with Sayew, which he co-wrote and co-directed with Kiat Songsanant. A comedy about a tomboyish young woman exploring sex and her sexuality, it won an honorable mention Asian Trade Winds Award at the 2003 Seattle International Film Festival.
He had also been approached by producer Duangkamol Limcharoen to write the screenplay for the romantic drama, The Letter, a 2004 Thai remake of a 1997 Korean film. The film was a hit, and with the screenplay, Kongdej became a sought-after scriptwriter.[1] He also wrote the screenplay for the 2005 Tony Jaamartial arts film, Tom-Yum-Goong.