Around 60 defendants - mostly soldiers but also some civilians - had been on trial since December in a special court in the capital Niamey for threatening the authority and security of the state.
Five soldiers deemed to be the leaders of the alleged putsch were sentenced to 20-year jail terms.
They included Captain Sani Gourouza, seen as the coup's mastermind, former senior officer Hamadou Djibo, Lieutenant Abdrahamane Morou and warrant officers Adamou Seyni and Mahamadou Halidou.
Gourouza had fled to neighbouring Benin, where he was arrested in April 2021 and handed over to the Niger authorities.
General Seydou Bague, a former chief of staff of Niger's army, received a four-year jail term.
The court acquitted around 30 defendants for lack of evidence, including ex-interior minister Ousmane Cisse, other soldiers and civilians.
Prosecutors had sought prison sentences ranging from two to 30 years.
Niger Jails Coup Accused
FILE: A soldier from the Niger Army stands guard, as supporters wait for the arrival of Niger President Mohamed Bazoum, in Sara-Koira in the west of the country, on September 11, 2021.
A Niger court on Friday handed prison terms ranging from two to 20 years to several soldiers accused of attempting to carry out a coup in 2021.
NIAMEY —