Nicky Jacobs punched the air after a jury cleared him of the murder of Pc Keith Blakelock.
He subsequently sat down and sobbed before being taken from the dock.
The 45-year-old's supporters in the public gallery including Winston Silcott - whose conviction for the murder of Pc Blakelock was quashed in 1991 - shouted "Yeah, yeah" and called out "Brother, brother" as the verdict was announced.
Courtenay Griffiths QC, for the defence, said: "I'm delighted, I think the jury reached exactly the right verdicts. Now I have to go and see my client."
More top news
A South east London man was charged under modern slavery laws with keeping a person in servitude and arranging the travel of another person.
Police have launched a hunt for conmen who duped couple in their eighties out of £20,000 in life savings by posing as gasmen.
A Met Police Sergeant attached to Croydon borough has been dismissed for failing to respond to fatal attack where man was stabbed 200 times.