The 23-year-old has joined the Florence-based club for €14m after three-and-a-half seasons at the Stade Pierre Mauroy.
Ikone joined Lille from Paris Saint Germain in the summer of 2018 and he made 37 appearances in the French top flight last season as Les Douges won the Ligue 1 title.
An official statement from La Viola read: “ACF Fiorentina is delighted to announce the signing of Nanitamo Jonathan Ikone from LOSC Lille on a permanent transfer.
“Born in Bondy (France) on 2 May 1998, Ikone was a key member of Lille’s Ligue 1 title-winning side last season. This year he made his Champions League debut, notching a goal and two assists in five appearances.
“The 23-year-old previously played for Paris Saint-Germain and Montpellier and has already racked up 157 appearances and 13 goals in Ligue 1.
“The winger also has four senior France caps and one goal to his name.
“Jonathan Ikone, who will wear the No.11 shirt at Fiorentina, will be officially unveiled as a Viola player at a press conference on Tuesday 4 January, at 11:00. The media conference will be managed remotely via Cisco.”
Fiorentina currently lie seventh on the Serie A table, six points outside the Champions League places.
