The body of the latest victim was found inside a Dodge pickup truck that officials originally believed contained only two people, the Tampa Bay Times reported Wednesday.
Because of severe burns, the two people removed from the pickup earlier have not been identified.
The crashes, which involved nearly two dozen vehicles, occurred when the Dodge pickup crashed into a tractor-trailer on the southbound side of I-75.
It happened just as visibility took a sudden drop due to fog and smoke.
Multiple investigations have been initiated to evaluate the highway patrol's decision to reopen I-75 about half an hour before the pileup occurred.
In addition to the 11 dead, 21 people were injured in the crashes that involved seven tractor-trailer rigs and 12 passenger vehicles.
On Tuesday the Medical Examiner's office released the name of Vontavia Kiara Robinson, 22, of Williston, Fla., as one of the victims.
She was driving a Pontiac Grand Prix and had a passenger who has yet to be identified yet, authorities said.