The Italian was one of two senior players, along with defender Scott Wootton, freed by the Whites on Friday.
Antenucci was the Yorkshire side's second top scorer this past season, scoring nine goals in total.
Despite this, the 31-year-old's exit was all but confirmed by himself on social media at the start of the month, and he is said to be courting interesting from as many as eight clubs in his homeland.
But another chance to prove himself in England could appeal to the former Torino player.
Birmingham, who finished 10th in 2015-16 - four points above Leeds, recently released strike pair Lee Novak and Wes Thomas and could view the skilful Antenucci as an ideal foil for top scorer Clayton Donaldson.
Reports earlier this month suggested Whites owner Massimo Cellino was keen to implement a British core at Elland Road next season, and Dundee forward Greg Stewart is the latest name to be linked with a move to West Yorkshire.