Fiorentina bag Behrami from West Ham
A club statement said the 25-year-old midfielder had signed a permanent deal for an undisclosed fee after the move had looked to be off earlier in January.
English Premier League bottom side West Ham have already replaced the former Lazio player with Gary O'Neil, 27, who arrived from Middlesbrough on a two-and-a-half-year deal on Monday.
Behrami made 63 appearances for the east London side, scoring five goals, after joining the club in 2008.
Fiorentina have been trying to sell rebel striker Adrian Mutu to a foreign club but latest media reports say the Romanian could stay in Florence having sacked his agent.