Jorginho scored from the spot kick after David Luiz was sent off for a challenge on Tammy Abraham.
Martinelli took advantage of N’Golo Kante’s slip to equalise for Mikel Arteta’s men after half-time.
Two goals from Cesar Azpilicueta and Hector Bellerin in the second half ensured both sides got a point each at Stamford Bridge.
Ferdinand told BT Sport: “To run that far and to have the composure to finish [for his goal] is brilliant.
“Martinelli is a centre-forward at heart. There’s too many players who sulk after being moved into a different position.
“The appetite and willingness was great. He’s showing the desire
Also speaking, former Chelsea star, Joe Cole also described Martinelli as the future of Arsenal.
He said: “This lad [Martinelli] is a very, very good player. He’s the future of Arsenal.”
