A car packed with explosives blew up near car dealerships in the Shia area of Bayaa in the south of the city. More than 50 people were injured.
At least 18 people died in another attack on used-car dealers on Wednesday and four were killed the day before.
The Islamic State group claimed Thursday’s blast, AFP reported.
Baghdad saw a wave of deadly suicide attacks by IS in the first few days of 2017, but the number had dropped until recently.
The IS group has stepped up its attacks since the Iraqi army, aided by US-led coalition strikes, launched its campaign to dislodge the Sunni militant group from its stronghold of Mosul in the north four months ago.
Wednesday’s attack targeted the Habibya area of Sadr City, a suburb in the north of the Iraqi capital. The car bomb on Tuesday took place in the south of Baghdad
On 2 January, at least 35 people were killed in a bomb blast in Sadr City, in an attack claimed by IS.