Judge Ezekiel Vaval gave the officers sentences ranging from two to 13 years in prison, The New York Times reported Friday.
He received frequent death threats during the three-month trial and traveled to New York during the holidays to write his decision free from pressure, officials said.
The stiffest sentences went to the former Les Cayes prison warden, Sylvestre Larack, and Olritch Beaubrun, the city's riot police chief who was tried in absentia after leaving the country.
The eight officers were charged with murder, attempted murder and other crimes for killing and wounding many detainees after a disturbance that occurred in January 2010, one week after a catastrophic Haitian earthquake.
Prosecutors charged the officers killed 20 detainees but the precise number of deaths and injuries is not known.
An independent commission found that the officers opened fire on unarmed inmates "deliberately and without justification."
The panel's findings contradicted an earlier official explanation for the deaths that was accepted by the Haitian government.