The duo have shaken hands with president Edoardo Garrone and both will now remain with the club until 2015.
Former Fiorentina, Lazio and Palermo boss Rossi took charge of the club in December and has guided the Blucerchiati to safety.
"As far as I am concerned, Delio Rossi will remain at the helm of Sampdoria next year," Garrone said.
Rossi added: "No more than a month ago I met president Garrone and we shook our hands.
"I hope I can be up to the task of this situation."