Medjani was brought to the club in 2003 by Houllier and loaned to second division Lorient in France in the 2004/05 season to gain experience, which he did in 19 out of 34 league games. Medjani has been captain of France's youth international teams for the last few years and lifted the respected Toulon trophy when France u-20 won it in the summer of 2005. Medjani was sold to first division Lorient in the summer of 2006. He only played nine league games in his only season at Lorient before being loaned and eventually sold to second division Ajaccio. Medjani played in 35 of Ajaccio's 38 Ligue 1 matches in 2011/12. In doing so, he passed a century of League appearances for the Corsican club. Medjani is of Algerian origin and played his first full international for Algeria in 2010.
Medjani spent a few years at Ajaccio before moving from Corsica to the French mainland and signing for Monaco in January 2013. He played in fifteen first-team matches for Monaco between February and the end of the season in May. He also continued to play in both competitive and friendly matches for his country, Algeria.
The central-defender had two loan spells during the 2013/14 season in addition to making 8 first-team appearances for his parent club, Monaco. He only played four times while on loan with Olympiacos in Greece in the autumn and was then loaned out to Valenciennes for the final part of the French season. Appearing for three different clubs in such a short space of time did not prevent him being named in Algeria's squad for the 2014 World Cup finals in Brazil. He then signed a three year contract with Turkish side Trabzonspor, from where he moved to Levante in January 2016. He played fourteen times for them in the second half of 2015-16 but after their relegation he left on a free transfer and remained in the Primera Division by signing for newly promoted CD Leganes. After just eight appearances he was on the move again the following January, returning to Trabzonspor where eh remained just six months. Staying in Turkey Medjani joined Sivasspor and in January 2019 left on a free transfer for Saudi Arabia side Ohod Al Medina, where he scored three ties in fifteen appearances in the second half of the Professional League season.