The blast occurred at 4:40pm local time as the market was crowded with people buying food for their evening meal.
Hoda Abdel-Hamid, Al Jazeera's correspondent in Baghdad, said there was widespread indignation in the city over the ongoing wave of devastation.
The bombing was the latest in a series of attacks against commercial targets in the capital as anti-government fighters seek to maximise the number of people killed before a planned US-Iraqi security sweep.
The explosion, which Nuri al-Maliki, the Iraqi prime minister, blamed on Saddam Hussein supporters and other Sunni fighters, shattered fruit and vegetable stalls, caved in shopfronts and left the smashed bodies of shoppers strewn in the street.
He said in a statement: "All Iraqis were shaken today ... the Saddamists and Takfirists have committed another crime."
In Washington, the White House called the suicide bombing an "atrocity" and pledged to help the Iraqi government bring security to Baghdad.
Earlier on Saturday, in the northern, ethnically mixed city of Kirkuk, seven car bombs, including a suicide attack, killed at least four people and wounded 37.
Two of the cars detonated outside the offices of the main Kurdish parties in the city.
Seven car bombs in Kirkuk killed at least
four people and injured 37 more [AFP]
The self-proclaimed Islamic State in Iraq claimed responsibility for the attacks in an Internet statement.
A police source said vehicles had been banned from the roads and entrances to Kirkuk sealed to prevent more car bombings.
In Iraq's north-west, a curfew was imposed in Mosul, Iraq's third largest city, after clashes between anti-government fighters and police in several neighbourhoods.
But violence continued despite the curfew. A car bomb hit an ambulance and killed an injured woman who was being taken to hospital and six mortar bombs struck the offices of the state-funded Iraqiya television channel.
Earlier in the day, a curfew had also been imposed on Samarra after six police commandos were killed when a police checkpoint just north of the city was attacked by armed men.
An Iraqi Sunni fighters' group believed to be linked to al-Qaeda in Iraq has announced that it had launched a new fighting strategy to encompass areas in Iraq beyond Baghdad.
|The Sadriya market blast on Saturday|
wounded more than 300 people [AFP]
An audiotape posted on Saturday on a website commonly used by the group purportedly bears the voice of Abu Abdullah Rashid al-Baghdadi, also known as Abu Omar al-Baghdadi, the head of The Mujahidin Shura Council.
In the 22-minute tape, al-Baghdadi said his new operation, dubbed Dignity, would counter George W Bush's plan to send 21,500 more troops to join the estimated 130,000 already in Iraq.
"We bring our Sunni people the good news of a plan ... wider and firmer with the power of God, that will not only include Baghdad, but all the areas inside the Islamic state."
The bombing in Baghdad came after Iraq's top Shia cleric, the Ayatollah Ali al-Sistani repeated his calls for calm from the Shia theological centre of Najaf.
"The Islamic nation is passing through difficult conditions and facing tremendous challenges that threaten its future," al-Sistani's new fatwa, or religious edict, said.
"Everybody knows the necessity for us to stand together and reject the sectarian tension to avoid stirring sectarian differences."