Do I need liability insurance for a rental car in Florida?

You are not required to purchase insurance from a rental car company. However you are required by law to have insurance. If you have your own insurance call your insurance company and ask what they cover for rental cars, then once you get to the rental car company ask them what their insurance covers, then use which ever one you feel is best for you.

If you do not have personal insurance, I would definitely take out the rental cars insurance.