The three men were convicted in June of involuntary servitude, harboring undocumented workers, interfering with interstate commerce by extortion and using a firearm.
Brothers Ramiro and Juan Ramos employed more than 700 farm laborers, many of them undocumented immigrants from Mexico.
They each were sentenced to 12 years and three months in prison and must forfeit real estate and personal property worth $3 million. Their cousin, Jose Ramos, was sentenced to 10 years, three months in prison.
Defense attorney Joaquin Perez said the Ramoses were scapegoats for a larger industry-wide problem.
"The whole thing is a farce," he said. "They are victims in this case because growers and other members of the industry have their heads buried in the sand."
The FBI and Border Patrol investigated after the Coalition for Immokalee Workers, in southwest Florida's farming region, called attention to the abuses.
Staff member Julia Perkins said it was the fifth case that resulted in convictions on similar slavery charges in as many years. She accused the state agriculture industry of looking the other way as contractors employ illegal aliens who have few rights.
"We hope that it will send a message that it's time for these abuses to stop," Perkins said. "The agriculture industry is complicit in some way."
State agriculture department spokesman Terrence McElroy said the industry should not be blamed for the actions of a few.
"Most Florida growers treat farm workers fairly," he said. "It obviously is outrageous conduct, and to suggest that it is condoned is unfair."
By Adrian Sainz