Is it illegal to drive while talking on a cell phone without a headset in Florida?

Yes! And think about it for a minute, it goes against reason to cut off one of your senses from being used to keep yourself safe!

Florida State Law §316.304 Wearing of headsets.-(1) No person shall operate a vehicle while wearing a headset, headphone, or other listening device, other than a hearing aid or instrument for the improvement of defective human hearing.