The blast in the densely populated majority-Shia suburb of Sadr City came as shoppers crowded the market buying food ahead of the Islamic festival of Eid al-Adha.
In January, the Islamic State group claimed responsibility for a rare twin suicide bombing that killed 32 people, also at a crowded market in Baghdad.Such violence was commonplace in Baghdad during the sectarian bloodletting that followed the US-led invasion of 2003, and later on as IS swept across much of Iraq and also targeted the capital.
The US-led coalition that had been supporting Iraq's campaign against IS has significantly drawn down its troop levels over the past year, citing the increased capabilities of Iraqi forces.