In Karrada, the streets were jammed with shoppers buying clothes and gifts ahead of a six-day public holiday beginning on Tuesday to celebrate the end of the fasting month.
Earlier, one person was also killed and three wounded by a roadside bomb in the district of Mansur, security officials said.
"The insurgents ... [want] to show there is no security in Baghdad," Qassim Moussawi, the Iraqi government's Baghdad security spokesman, told the Reuters news agency.
He said that authorities expected there to be more attacks in the capital, and some would be difficult to prevent, as bombs were being assembled inside the neighbourhoods they were targeting, instead of passing through police checkpoints.
A Kurdish mayor of a northern Iraqi town was wounded in a separate roadside bombing in Saadiyah near the Kurdish-dominated city of Khanaqin, along with six of his guards, police said.