The piece which survived a fire during the Battle of Waterloo was taken from the wall of a chapel in the chateau of Hougoumont.
It was feared the six foot cross was snatched by a collector or a local thief but after an anonymous tip off, Interpol tracked it down to a local market in Wallonia.
Police are now investigating how it came to be there.
According to the Telegraph, Nathalie du Parc, president of the board of municipalities that own the location where it was stolen from, said: "When I first heard the news, I didn't believe it. I was sure it was not true and it was someone trying to sell us a copy or something.
"People who have seen it since it was rediscovered have become very emotional. It is the last witness of the battle."
The crucifix has now been locked away in what's been described as a 'safe place'.