Police have been investigating a series of cases in which at least 18 horses in Miami Dade and neighbouring Broward County have been been slaughtered and cut up for meat.
Detectives believe there is a live black-market trade in horse meat, which can fetch up to $US20 a pound.
The arrested men have been named as Roberto Chavez 53, and Ricardo Olivarez, 45.
Detective Edna Hernandez said the Miami-Dade Police Department Agricultural Unit and Intergovernmental Bureau arrested the pair yesterday (Tuesday local time) for illegally selling horse meat for human consumption.
Hernandez said inquiries unearthed information that Chavez and Olivarez were selling horse meat from a ranch in Southwest Miami Dade.
"According to investigators, Chavez is the owner of the ranch and Olivarez was his employee.
"Upon receiving information that Chavez and Olivarez were selling horse meat from the ranch, an undercover detective went to the ranch and purchased 10 pounds of suspected horse meat for $US50.
"The meat was sent to the US Department of Agriculture for testing, which revealed the meat came from a horse. Investigators then returned to Chavez's ranch and arrested him and Olivarez.
"Investigators believe that this is an isolated incident and that Chavez and Olivarez were not involved in any prior reported case of slaughtered horses."
Chavez and Olivarez will face charges of doing business without a license. Chavez will also face a charge of violating probation.
Investigators last month arrested two men as part of their inquiries.
Luis Miguel Cordero, 18, of Hialeah, is alleged to have slaughtered one horse and was intending to carry out another killing on the evening of his arrest.
Santiago Cabrera, 19, of Hialeah, was also arrested as a co-defendant. Investigators said at the time of his arrest that they learned "through investigative leads" that Cabrera was involved in the slaughtering of horses at two separate locations.