Mann, 59, was executed by lethal injection at 7:19 p.m. EDT at a state prison in Starke, the Tampa Bay Times reported. Corrections officials said he responded "Uh, no sir" when asked if he had any final words.
Mann was convicted in 1981 of killing Elisa Nelson, 10, whose throat was cut and her skull crushed by a single blow from a concrete block.
Elisa was abducted while riding her bicycle to school in Palm Harbor in 1980. Authorities suspect he had intended to molest her, then killed her when she tried to escape.