Army Commander Frank Bainimarama said he had taken over the role of the president and is dismissing Prime Minister Laisenia Qarase.
"The takeover will not be permanent, tomorrow I will summon the chief executive officers and charge them with the duty of running their own ministries until an interim government is appointed," Bainimarama said.
The army commander had repeatedly threatened to topple Qarase's government, which won a second five-year term in May, claiming it was corrupt and soft on those behind Fiji's last coup, in 2000.