Cassano has expressed a desire to leave AC this summer following the sale of key men such as Thiago Silva and Zlatan Ibrahimovic.
He will swap life with the Rossoneri for that with the Nerazzurri.
Pazzini will head in the opposite direction, meaning both clubs retain their current striking stock.
Cassano and Pazzini both boast enviable strike rates in Serie A and once formed a prolific partnership at Sampdoria.
It is understood that the duo will undergo medicals on Tuesday before finalising their respective switches.
“The exchange has yet to be concluded but who would not like Cassano?” Inter president Massimo Moratti told gazzetta.it.
Pazzini told Sport Mediaset: “Am I pleased to take the place of (Filippo) Inzaghi? I’m happy, very happy.
“I found out about this agreement yesterday and I’m very happy.”