The bomber detonated a belt rigged with explosives in the outdoor market in the primarily Sunni area of Sadiya, southwestern Baghdad at 0410 GMT on Tuesday.
In a separate attack, two civilians were injured when a roadside bomb singling out a US convoy blew up.
One civilian was killed and two more wounded in a rocket attack on a residential neighbourhood in northern Baghdad.
Another person was killed and nine more injured in Baghdad when a parked car bomb blew up near a Shia mosque in Karrada in the city centre.
Meanwhile, authorities in Baquba, 60km northeast of Baghdad, said four gunmen were killed in a morning clash with police.
In a further attack, one civilian was killed and three others were injured when unidentified gunmen stormed the house of a Shia family in al-Muqdadiya, about 90km north of Baghdad.
US soldiers killed
Seven US soldiers have been killed in a series of incidents in Baghdad and western Iraq.
One soldier was killed in southwest Baghdad when his patrol came under fire, while two others were shot dead in separate attacks in the north of the capital, all on Monday.
A soldier died on Sunday night of wounds inflicted by a roadside bomb west of the city.
Two marines from Regimental Combat Team Seven, which operates in the western reaches of the Euphrates valley in Iraq's al-Anbar province, died from injuries received during fighting, one on Sunday and one on Saturday.
Late on Monday, the US military reported the death of another soldier whose unit had come under fire in Baghdad.
The latest fatalies bring the number of US military casualties in Iraq since the March 2003 invasion to 2,718.