'Islamic State has fallen' says top Iraqi commander
"Their fictitious state has fallen," Iraqi military spokesman, Brigadier General Yahya Rasool, told state TV.
In 2014, IS leader Abu Bakr al-Baghdadi declared a "caliphate" from the historic Mosul mosque.
"Counter-Terrorism Service forces control the Nuri mosque and al-Hadba (minaret)", the Iraqi Joint Operations Command said in a statement.
The Battle for Mosul began over eight months ago and IS has been making a last stand in the historic Old City.
The militant group blew up the Grand al-Nuri mosque on 21 June in increasingly desperate resistance to the advance of Iraqi forces, with Iraqi Prime Minister Haider al-Abadi declaring it an "official declaration of defeat".
The loss of the iconic 12th century minaret - one of the country's most recognisable monuments sometimes referred to as Iraq's Tower of Pisa - left Iraqis shocked.
IS claimed on its Amaq propaganda agency that the site was hit in a US air strike, but the US-led coalition said it was the group who had destroyed the historic religious building.