La Viola were also desperate for a victory to keep alive their slim hopes of Champions League qualification as the match started at a frenetic pace.
Kurtic then spurned a wonderful opportunity for the visitors as his scuffed shot drifted wide of the target.
Stevan Jovetic then had a goal disallowed for offside but Fiorentina finally broke the deadlock five minutes before the break.
Slick passing from Borja Valero and Juan Caudrado created a chance for Toni at the far post and the veteran striker made no mistake, sliding in to score with the help of a late deflection.
Palermo introduced talisman Fabrizio Miccoli midway through the second half but the diminutive forward was unable to engineer a response.