Mr Bloomberg, the former Democratic mayor of New York City, has raised more than $16 million (£12.5 million) in funds to pay-off felons’ debts and secure their voting rights in the crucial swing state.
Florida’s attorney general on Wednesday said that warranted both state and federal investigations.
"I have instructed the Statewide Prosecutor to work with law enforcement and any Statewide Grand Jury that the Governor may call," said Ashely Moody, the attorney general, in a written statement.
Mr Moody also sent letters to the Florida Department of Law Enforcement and the FBI calling on Mr Bloomberg to be investigated.
Republican governor Ron DeSantis had asked Mr Moody to review allegations that Mr Bloomberg and the Florida Rights Restoration Coalition (FRRC) had violated the laws on election incentives with those donations.
Voters had already approved a constitutional amendment to restore most felons' voting rights upon completion of their sentences, with some exceptions, in 2018.
The state’s Republican-held Legislature later argued that rights wouldn't be restored until all fines, court fees and restitution were paid, when the law was introduced.
The funds raised by Mr Bloomberg were targeted for felons who registered to vote while the law was in question and who owe $1,500 (£1,117) or less, accounts for some 31,100 people, his staffers said.
"Florida Republicans will stop at nothing to prevent people from voting, and this is another ploy to suppress the voices of those trying to regain their right to vote," Nikki Fried, Florida's only statewide elected Democrat and a member of the Cabinet said in a statement.
Florida’s 29 electoral college votes are crucial to Donald Trump's reelection chances in November.