The 12-year-old was assaulted after leaving his aunt's house with his 10-year-old brother.
Officers said the attacker pounced as the young boys walked along Brockburn Road, in Pollok.
During the attack, at around 10.10pm on Sunday, the boy was punched and racially abused.
He was taken to hospital and kept in as a precaution because of a pre-existing medical condition.
Following treatment, he was released yesterday.
Police said the suspect is white, between 15 and 16-years-old, of slim build, with short light blond hair.
He was wearing a dark coloured body warmer, red short sleeved shirt and grey jogging bottoms.
Inspector Fraser Lennox, from Pollok Police Office, said: "The boys had been at their aunt's house nearby and were making their way along the footpath when the assault took place.
"Officers are checking CCTV and carrying out door to door enquiries in the area in an effort to trace the youth responsible,
"We would still appeal to anyone who was in the area, who either saw the incident or who may have seen the boys or their attacker in the area, either prior to or afterwards."
Anyone with information is asked to contact police at Pollok Police Office on 101.