West Midlands Police said the shooting occurred just before 17:30BST on Bowyer Road in Alum Rock.
The boy was taken to hospital to be treated for "potentially life-threatening" gunshot injuries, police said in a statement.
"Although this happened near a mosque, at this stage we do not believe the shooting to be connected to this place of worship."
The statement added: "We understand this is extremely worrying for people in the area, and local officers will be remaining there to speak to anyone with concerns."
Police are urging anyone with further information to get in contact or speak to Crimestoppers.
