Abdoun, capped 11 times by Algeria, has put pen to paper on a three-year deal at the City Ground.
The 27-year-old, who had a brief loan spell at Manchester City in 2007, was raised in France and spent his youth career with Paris Saint-Germain and Ajaccio before opting to join Kavala in Greece.
Despite Kavala's relegation from the top flight in 2011, Abdoun was a shining light and his performances earned him a move to Olympiacos where he scooped a second successive league title.
He remained a pivotal figure during the 2012/13 campaign, notching eight goals in a season which saw him pick up another league winners' medal and experience Champions League football against the likes of Arsenal and Schalke.
- Sports & Recreation