It's the state's highest rate on record, since data was first recorded in 1970.
Florida's unemployment rate for March 2010 is 12.3% after seasonal adjustment, according to the Agency for Workforce Innovation.
Statewide, 1,138,000 people out of a labor force of 9,269,000 did not have full-time jobs in March.
The latest number is slightly higher than February's revised rate of 12.2%, and 2.7 percentage points higher than the same month last year, the Agency said.
Pasco County has the highest rate of all Gulf Coast counties, ranking sixth in the state with 14.0% unemployment. Lee County is next, at 13.5%, followed by Manatee (12.9%), Sarasota (12.5%), Collier, Hillsborough and Pinellas (all 12.3%).