The former France international takes charge of the Ligue 2 side in place of Helena Costa after previously working as assistant for the France women's national team
The French side were in the market for a new boss following previous coach Helena Costa's decision to resign just one day after she was officially presented as the new woman in charge.
Costa accused Clermont of amateurism and disrespectful behaviour, saying that she was not kept in the loop over possible signings and the club's pre-season schedule, leaving her with no other choice but to step down.
The 39-year-old Diacre played her entire active career for Sochaux and made over 100 appearances for the France national team before hanging up her boots in 2006 due to a knee injury.
Diacre has previously been at the helm of Sochaux's women's side and was assistant to Bruno Bini for the France women's national team.
She became the first woman to obtain the necessary papers to coach in Ligue 1 and Ligue 2 earlier in 2014 and is now set to be the first woman to take charge of a professional club in a match in the top two tiers of any European league in the men's game.