Siani moved to Europe joining Anderlecht in July 2005 before leaving for Zulte-Waregem on a half-year loan a year later. In the 2007–08 season he played one season on loan at Union Saint-Gilloise.[3] One year later, he signed to Sint-Truiden on loan.[4]
On 11 July 2018, Al Jazira has signed Cameroonian midfielder Sébastien Siani for on seasons by buying the player's card from Royal Antwerp represent Al Jazira from the new season of the UAE Pro-League.[5]
In July 2021, after being a free agent for a year, Siani signed a two-year contract with Knokke.[6]