The Serie A club confirmed that the former Napoli boss had stepped down by mutual consent.
"The company immediately set to work to identify a technical choice that will guide the Viola team towards the results that Fiorentina and the city of Florence deserve," Fiorentina said.
Gattuso, who took the Fiorentina job just two days after leaving Napoli, is reported to have had disagreements over the club's transfer plans.
His agent, Jorge Mendes, is said to have proposed signings such as Porto's Sergio Oliveira and Goncalo Guedes of Valencia, but Fiorentina's management wanted to explore more affordable options.
According to La Gazzetta dello Sport, former Lyon boss Rudi Garcia, ex-Leicester City coach Claudio Ranieri and Walter Mazzarri, most recently at Torino, are candidates to succeed Gattuso.
Fiorentina finished 13th last season, with just nine victories from 38 league games.