Juress Kika, 19, Jade Braithwaite, 18, and Michael Alleyne, 20, were convicted of murder at the Old Bailey.
After being led into court in handcuffs, the three Londoners were remanded in custody for sentencing today.
Ben and his friends had been to a bar to celebrate the end of their GCSE exams when a row broke out in Islington, north London, on June 29 last year.
Although the confrontation had nothing to do with him, Ben was chased along the street with other youngsters and stabbed to death when he stopped running.
He was stabbed 11 times in five seconds by the three youths in revenge for the “disrespect” shown to Braithwaite earlier.
Former EastEnders actress Brooke Kinsella, 25, sat with her fingers crossed and burst into tears after the verdict.
Her parents George and Deborah shouted “yes” and wept as they were supported by other family members.
It was the end of a tense six weeks during which they attended each day of the trial.
Outside court, they were greeted by around 30 friends and family, who applauded them.
The soap star, who had appealed to youngsters to come forward and help police, said: “I am overjoyed.
“It’s awful, awful, but we got all we needed — it’s justice. There is never going to be enough justice but we have got it now.”
During the trial, aspiring footballer Braithwaite and Alleyne tried to blame each other, while Kika refused to give evidence.
Nicholas Hilliard QC, told the court: “No one suggests Ben Kinsella was anything other than totally blameless.”
Young friends of Ben had given evidence to the court and some broke down as they recalled the events of the night.
Some 400 people joined the family to march against knife crime following his death.