The Syrian Democratic Forces said the handover would not be immediate, with SDF fighters still combing the city of Raqqa.
The Joint Operations Command said Iraqi forces held all 29 districts of the city and were pursuing final mopping up operations.
Amnesty International said on Tuesday tactics used by Iraqi forces and their US-led coalition allies in the battle for Mosul violated international humanitarian law and might amount to war crimes.
Iraqi Prime Minister Haider al-Abadi was poised to declare victory over Islamic State in Mosul on Monday as only a few dozen militants put up resistance in the city where their leader declared a caliphate three years ago.
Key members of the US-led coalition fighting the Islamic State group in Iraq and Syria meet in Copenhagen on Tuesday to assess the campaign's next steps as the jihadists' "caliphate" collapses.
Ministers from the 68-nation US-led coalition fighting the Islamic State group meet in Washington to hear more about US President Donald Trump's plan to destroy the jihadists' remaining strongholds in Iraq and Syria.
Air strikes killed 23 civilians, including eight children, on Thursday in countryside around the northern Syrian city of Raqqa, the Islamic State's base in Syria, a war monitoring group said.