There was no immediate claim of responsibility for the blast at a mosque in the predominately Shia neighbourhood of Hay al-Amil.
The funeral was for a member of the Hashid Shaabi, a government umbrella group seen as a critical force in the battle against Islamic State.
The militia fighter was killed in battle against the militant group in Iraq’s western Anbar province, police said.
Also Friday in Baghdad, a roadside bomb detonated at a shrine in Sadr City, killing at least five people and wounding 15, police officials said.
Hospital officials confirmed the casualty figures. All officials spoke on condition of anonymity as they were not authorised to talk to reporters.
Iraq has been afflicted by sectarian conflict since shortly after the US-led invasion that toppled Saddam Hussein in 2003.
The rise of Islamic State has exacerbated those tensions and prompted US-led air strikes on the militants in areas of Iraq and neighbouring Syria where the jihadists aim to establish a modern-day caliphate.
Following its blitz last year, the Islamic State group now holds about a third of Iraq and neighboring Syria.
Since the emergence of IS, Baghdad has seen near-daily attacks, with roadside bombs, suicide blasts and assassinations targeting Iraqi forces and government officials, with significant casualties among the civilian population.
The violence has killed hundreds and displaced tens of thousands of Iraqis.
The 68th Anniversary of the Founding of the People’s Republic of China.
— The Daily Mail - People's Daily