Papadopoulos was born in Gagarin, Uzbekistan, USSR. He started his professional career in 1999, playing for Akratitos FC in Greece. In 2001, he moved to Burnley in England. He stayed at Burnley for two seasons, in which he played 39 games and scored 3 goals.
Papadopoulos returned to Greece in January 2012 to play for Levadiakos. In the Summer of that same year, he signed for Panthrakikos. In the summer of 2013 he moved for one year to Atromitos Athens, followed by a transfer in the summer of 2014 to PAOK again for one year. In the summer of 2015 he moved yet again for just one year to Asteras Tripoli. In the summer of 2016 Papadopoulos returned for his second spell at Atromitos Athens. In the winter of 2017 he signed his last contract at Panaitolikos where Papadopoulos announced his immediate retirement on September 23, 2017.
Papadopoulos has won 22 caps and has scored 2 goals for Greece. He was European Champion with his national team at 2004 European Football Championship where he came on as a sub in the final. He was the youngest and last member to retire of the golden squad of 2004.