He withdrew from the 2004 Summer Olympics, held in his home country, after a doping violation (failed to attend drug test).

Kenteris won his heat # 5, defeating then 100 m world record holder Maurice Greene, but did not start the quarter-finals due to injury.

Although Kenteris had established himself as a medal-winning national and European sprinter, few had heard of his name when he surprised by qualifying for the 200 m final at the 2000 Summer Olympics in Sydney.

Although defending Olympic champion Michael Johnson and reigning world champion Maurice Greene did not compete, still nobody had included Kenteris in the list of medal favourites despite his being the fastest European at 200 m that summer with 20.25 seconds from June, but Kenteris raced to the gold medal with a time of 20.09, denying Britain's Darren Campbell and Ato Boldon of Trinidad and Tobago.

This performance still stands as the national record in 200 m. The next year, Kenteris took part in the 2003 European Cup in Florence where he won the 200 m gold (20.37) and 4 × 400 m relay silver (3:02.69).

However, on the day prior to the Games, Kenteris and his training partner Ekaterini Thanou failed to attend a drug test.

In the ensuing doping scandal, Kenteris and Thanou announced their withdrawal from the Games on August 18, after a hearing before the Disciplinary Commission of the IOC, for what they described to be "in the interests of the country".

In May 2011 he was (along with Thanou) given a suspended jail sentence of 31 months, after being charged with staging the crash, but an appeals court overturned this ruling.