Can my prior convictions be used against me in a Florida drunk driving case?

Yes, if you have a prior DUI history and you're being sentenced for a DUI, then absolutely those prior DUI convictions can be used against you. However, if you're at trial, it's likely that the jury is not going to hear about any prior DUI convictions because it's inadmissible and it's irrelevant to the case at that time. However, if the door is open, then the jury may hear about your prior record.