TG became chairman of the Championship club in May 2010 but will now be "embarking on a new career", it has been confirmed.
A statement on Cardiff's website said: "We wish to confirm that Dato Chan Tien Ghee (TG) has resigned as chairman and director of Cardiff City with immediate effect.
"TG is embarking on new career and business pursuits that requires his full attention. Given constraints of time and distance, TG believes he is unable to meet the demands of his position as chairman and board member.
"We are greatly indebted to TG who since joining in 2010 has been instrumental in the progress of the club to where it is today, and we wish to record our deep appreciation for his invaluable contributions and efforts. We wish TG all the very best in his new undertakings."
Cardiff currently sit top of the Championship by eight points with a game in hand.