He will be the first Italian to drive for Ferrari in his home Grand Prix at Monza since Ivan Capelli in 1992.
Nicola Larini finished second for Ferrari in the San Marino Grand Prix at Imola in Italy in 1994.
Force India boss Vijay Mallya had denied the rumours earlier this week, even when team member Ian Phillips confirmed them to the BBC on Monday.
The last Italian to win the Italian Grand Prix was Ludovico Scarfiotti in 1966, driving for Ferrari. Can Fisichella become the first driver to emulate his feat in 43 years?