Born in Clermont-Ferrand, Casanova played for Cournon, Vichy, Le Havre, Marseille and Toulouse.

At Marseille, he made no professional appearances, but was on the bench at the 1991 European Cup Final, which the team lost to Red Star Belgrade in Bari.

[5] He was dismissed in March 2015, with the club three points from safety in 18th with nine games to play; he was Ligue 1's longest-serving incumbent manager at the time.

[6] On 13 June 2016, Casanova was named as the new manager of Ligue 2 club Lens, succeeding Antoine Kombouaré on a two-year deal with the option of a third.

[11] Despite improving on their performance, he was unable to fend off the looming disaster and three rounds before the end of the season, the club's relegation was already confirmed with a twelve point deficit.