The Italian club have been busy on transfer deadline day, buying the Serb and temporarily offloading the Peruvian, adding to the loan signing of Migliaccio earlier today
Tomovic signed from Genoa on a co-ownership basis on Friday, with the two clubs sharing a 50 per cent stake in the player.
The defender was loaned out to Lecce last season and was a regular for the side with 49 appearances, despite their relegation to Serie B.
Vargas's loan move to I Rossoblu has also been completed. The Peruvian international has played for Fiorentina for the last four seasons and has been an important part of the team, playing 124 times.
Viola snapped up Giulio Migliaccio on a loan earlier today.
Tomovic and Migliaccio could make their first appearances for Fiorentina when they travel to Napoli on Sunday.