Last night, the two clubs reached an agreement over a 12-month loan for the Italian forward, with Samp having the option to make the deal permanent at the end of this season.
Samp will pay £800,000 of Cassano's salary, with the remaining £2 million being covered by Real.
Samp chief Beppe Marotta said: "By now we have passed all obstacles. We believe a lot in this operation."