Luis Miguel Cordero
His accomplice, 19-year-old Santiago Cabrera, who also admitted to butchering the two horses, was jailed in December for five years, less the 18 months already served.
Cordero is likely to be deported to Mexico following his jail release.
Cordero and Cabrera had entered two private farms in Miami-Dade County in September 2009 and led two horses out of their stalls, then butchered them to obtain meat for selling on the black market.
The killings were among a spate of more than 20 in south Florida that had local horse owners up in arms.
New laws have since been passed in Florida introducing harsher penalties for butchering horses for meat.
Reward money was offered over the string of killings and the pair were caught when Cabrera tried to dob in his friend, Cordero, for the reward money.