The 33-year-old Canadian international striker, who was released by Fulham at the end of last season, has signed a two-year deal with the Greek side.
"From the discussions I've had with the people at Xanthi, it was clear that they are an ambitious team, which appeals to me because I want to play in a team that have prospects," Radzinski told reporters in Greece.
Radzinski made over 100 appearnces during his stay at Craven Cottage having joined from Everton in August 2004.