Learco Chindamo, 17, who stabbed Mr Lawrence to death outside his school as he defended a pupil, showed no emotion as the Court of Appeal dismissed his bid for freedom - watched by Mr Lawrence's widow, Frances.
The Lord Chief Justice, Lord Bingham, sitting with Mr Justice Douglas Brown and Mr Justice Kay, rejected criticisms of the summing-up of Judge Neil Denison, at the Old Bailey, in October 1996.
"We have to say that in the light of all the arguments advanced we are in no doubt that this conviction is safe."
Mr Lawrence was attacked in December 1995 outside St George's school in Maida Vale, west London, when a gang of 12 youths led by Chindamo went to attack a boy.
He was punched and stabbed by Chindamo and died the same evening.
Chindamo, who was 15 at the time of the stabbing and was a member of the Wo-Sing-Wo gang - which aspired to be the juvenile equivalent of the Triads - has always claimed that another youth was the killer.
He claimed he was the victim of mistaken identity as the other youth was wearing his jacket, and that he was 30ft away from the murder scene.
Chindamo was ordered to be detained indefinitely after a jury found him guilty of the crime.Reuse content