Authorities have described the suspects as Oromo Liberation Front (OLF) rebels trained in Eritrea, and said they were caught with explosives smuggled in from the Red Sea state and neighbouring Djibouti.
The bombers were accused of planning to strike a hotel where several heads of state were staying, as well as an open market west of the capital Addis Ababa, as part of efforts to destabilise Ethiopia.
“Four suspects were sentenced to life in prison, six to 25 years behind bars, one to 14 and three to nine years in jail,” a Justice Ministry official told Reuters.
Eritrean and OLF representatives were not immediately available for comment.
Ethiopia routinely accuses Asmara of supporting rebel groups, and declared in April it would support Eritrean guerrillas fighting to overthrow President Isaias Afewerki.
Both sides have often traded tough rhetoric since their 1998-2000 border war, which killed around 80,000 people and left the frontier demarcation unresolved.
Eritrea was part of Ethiopia until 1991, the culmination of a 30-year secession war by rebels under Afewerki.