Erdei won the WBO light heavyweight title and the distinction of "lineal" light heavyweight champion by winning a unanimous decision over Julio César González, January 17, 2004. Gonzalez had won the title three months earlier by outpointing long-reigning champion, Dariusz Michalczewski.
Erdei successfully defended the title eleven times.
On November 13, 2009 he relinquished his WBO light heavyweight title and moved up to cruiserweight. Erdei defeated Giacobbe Fragomeni on November 21, 2009 for the WBC cruiserweight title. The fight was decided on the inside, with Fragomeni (26-1-1, 10 KOs) needing to win only one more round to earn a draw, but unable to do so. Erdei started fast, circling throwing punches in bunches of five or more, frustrating Fragomeni.
After winning a share of the cruiseweight title, Erdei has relinquined that belt and returned to the light heavyweight division.
There is talk of Erdei fighting newly-crowned WBO light heavyweight champion Nathan Cleverly.
His new promoter, Lou DiBella, said in 2010, "Zsolt needs to fight and stay active and stay in the consciousness of fans, plus he will be on the international broadcast."
When he's fought in the US, Erdei has drawn a large contingent of Hungarian fans who waive flags, chant and sing throughout the fight.
Major World Titles
WBO Light Heavyweight
MD 12 Giacobbe Fragomeni - 2009
UD 12 Thomas Ulrich- 2006
SD 12 Hugo Hernan Garay - 2005
MD Hugo Hernan Garay- 2004
UD 12 Julio Gonzalez - 2004
Erdei boxed at the 2000 Summer Olympics. He won a bronze medal in the middleweight division.
"Zsolt Erdei has held a title belt for quite some time...At 30-0, he is probably the least respected, most ignored unbeaten longtime title holder in the history of the sport."
Jim Lampley, HBO Sports