The 20-year-old rose through the ranks at Fiorentina's academy but never had the chance to make his Serie A bow in Stefano Pioli's team.
He joins the Crusaders in his quest for regular playing time and he teams up with countryman Yves Baraye and Cote d'Ivoire winger Gervinho.
"Parma Calcio 1913 announces the signing of Abdou Diakhate (Dakar, Senegal, 31 December 1998) from ACF Fiorentina. The player has signed a contract running until 30-06-2023," read a club statement.
Parma, placed 12th in the Serie A table with 28 points from 22 outings, are five points adrift of a place in the Europa League playoff spot.
Diakhate was an unused substitute at the Stadio Ennio Tardini as Parma bowed 3-2 to SPAL on Sunday.