Video and photos of the boy sitting dazed and bloodied in an ambulance were shared widely on social media, with many expressing shock and outrage.
A doctor identified him as Omran Daqneesh, 5, who they said was treated for head wounds on Wednesday night.
It was not immediately clear what happened to the rest of his family.
Fighting between Syrian government forces, backed by Russian air strikes, and rebels has escalated in Aleppo in recent weeks, reportedly leaving hundreds of people dead.
The pro-opposition Aleppo Media Centre said the pictures of the boy were taken in the rebel-held Qaterji district of Aleppo on Wednesday, after air strikes that left three people dead and 12 injured.
The video shows the boy being carried out of a damaged building by a medic and then placed on a seat in the back of an ambulance, covered in dust and with a blood-covered face.
The medic then leaves the vehicle and the boy is left sitting quietly, appearing stunned by the ordeal. He runs his hand over his face and looks at the blood before wiping it on the seat.
He is later joined by two other young children and a man injured in the air strike.
A doctor in Aleppo, Osama Abu al-Ezz, told the Associated Press that the boy in the ambulance was brought to a hospital known as M10 following the attack on Qaterji with head wounds, but no brain injury, and was later discharged.
Raf Sanchez of the Daily Telegraph also tweeted a photo showing the boy lying down on a stretcher with a bandage covering his left eye.
“The stunned, bloodied face of a child survivor sums up the horror of Aleppo,” wrote Adib Shishakly, a member of the opposition Syrian National Council.
The Local Co-ordination Committees, an opposition activist network, also said three people were killed in the air strike and reported that Russian warplanes had fired a “vacuum missile”, an apparent reference to fuel-air explosive munitions. – BBC