The Genoa-based outfit are third from bottom, just three points clear of the foot of the table, having won only two of their opening 12 league games this season.
Rossi, who was appointed the Blucerchiati boss last December, has paid the price for this poor form by losing his job, which was the 16th of his journeyman career.
A club statement read on Monday night: "Sampdoria announces that it has relieved Delio Rossi and his staff of their duties.
"The company would like to thank everyone for their commitment and professionalism over these past months and wish you the best of luck.
"The management of the first team will be temporarily entrusted to Francesco Pedone."
Pedone made 33 appearances as a Sampdoria player and has had two coaching spells with the club.