Smadja was born in Ofakim, Israel, to a family of Sephardic Jewish (Tunisian-Jewish) descent. He won the Olympic bronze medal in judo at the 1992 Summer Olympics the "under 71" category. In 1995, he won a silver medal at the 1995 World Judo Championships. The next year, he could not repeat his Olympic success at the 1996 Summer Olympics.