The 22-year-old, capped by Belgium at U21 level, was a youth player with Standard Liege and Anderlecht before moving to Italian side Avellino in 2016.
Hibs boss Neil Lennon told the club website: “Stephane comes to us with great pedigree, having played a good number of games in Serie A for someone of his age.
“We’ve watched a lot of him and we think he can add a lot to the group in terms of his energy, dynamism and willingness to go box to box."
