The suicide attack targeted a checkpoint along a route used by Shia pilgrims in the northern Baghdad neighborhood of al-Shaab.
Iraqi police said four soldiers who were guarding the route were among those killed, media reports said.
Security measures have been stepped up ahead of Arbaeen, which falls on Wednesday, December 2, this year.
Every year, millions of Shia Muslims march toward they holy city of Karbala to mark Arbaeen, the 40th day after the martyrdom anniversary of Imam Hussein (AS) and his companions in the 680AD battle of Karbala.
The Arbaeen ceremony marks the largest religious gathering in the world.
Last year more than 20 million Shia pilgrims converged on Karbala for Arabeen.