Jalan was walking to school with his friends in Hayes when he was set upon by the defendant in June 2021. He died from stab injuries.
“Whilst it is apparent that there was some form of grievance between these two teenagers, nothing can justify the taking of another life,” said Met Police’s Detective Inspector Mike Nolan.
The teenager was found guilty at Harrow Crown Court of the manslaughter of Jalan and possession of having an article with a blade or point in a public place.
He is scheduled to be sentenced on September 8.
Police were called to Blyth Road at around 8.30am on June 11 and found Jalan with stab wounds. He died at the scene.
CCTV cameras captured the moment the suspect – who was just 15 years old at the time – followed Jalan and his two friends.
He produced a large Rambo-style knife from his waistband before chasing after Jalan and slashing him across the face and stabbing him in the chest.
He then fled the scene and made his way to school but was arrested a short time later.
Witnesses told officers that the suspect appeared to have been filming the attack on his phone, the Met said, but he refused to answer any questions during an interview.
Mr Nolan said: “The defendant attempted to justify his actions by claiming self-defence, but the evidence and eye witness accounts confirm that he was carrying a large knife in a gloved hand. Whereas Jalan was unarmed, and tried to use a traffic cone to fend off his attacker.
“Once again another teenager has lost his life to knife crime, and another family is grieving the loss of a child. Our thoughts are with them today.
“We are determined to do whatever is necessary to crack down on violence, but we need the help of our communities and partners to tackle this problem.”