Baptista Adjei, also 15, was stabbed on Stratford Broadway outside Stratford Shopping Centre on Thursday.
His alleged killer can not be named for legal reasons.
Officers were called to Broadway in Stratford, east London, shortly after 3pm following reports of a stabbing.
Baptista was attacked on or after getting off a bus which had stopped close to the Stratford Shopping Centre.
Police said a 15-year-old boy was charged with murder the following day. He will appear in Stratford Youth Court on Monday.
Police and witnesses said the teenager’s friends and passers-by rushed to help after he was knifed outside a McDonald’s at the shopping centre.
But police and paramedics found him with “critical injuries” and, despite battling to save his life, he was pronounced dead at the scene at 3.49pm.
Baptista’s aunt, Aretha Adjei, said her nephew was a “fun-loving boy”, who would “always make you laugh”.
She added: “He was a nice boy, the fact that he died in his school uniform is horrific.
“He had just finished school. He spoke to his mum on the phone about coming home after popping in to McDonald’s with a friend. Twenty minutes later he was stabbed to death.
“His mother is not coping well. She only has two children. You can’t imagine her pain. She keeps saying how she should have gone and picked him up.
“He was a fun-loving boy, very popular with everyone in church, everyone in the street knew him. He would come and put his arms around you. He would always make you laugh.
“No-one could say a bad word about him, he would never join a gang or a group. That’s not him.”
The teenager’s former football team, Mindset FC, tweeted that Baptista was a “very humble boy, with great manners and very talented”.
It added: “Dark moment at Mindset as one of our former players from the U16s last season went to sleep today at Stratford due to knife crime.
“All of us at Mindset have the family in our thoughts and prayers. RIP Bap.”