Midfielder Poli spent last term on loan at the San Siro, and Inter seemed set to take up the option of agreeing a permanent deal for a player who turned out over 20 times for the Nerazzurri last term.
The two clubs could not agree a permanent deal with the Italian international.
"It’s true, I did expect Inter to take up their option on me,” said Poli.
“However, Sampdoria boss Ciro Ferrara then made me understand that he wanted me in his Samp first team and I’m happy to be back.
“I also have to thank the fans who made me understand that I have returned ‘home’ for the way they welcomed me at our presentation.”