Hundreds of protesters have gathered outside Tottenham police station to hold a vigil for Mark Duggan.
His relatives and supporters have called for the event to remain peaceful, while the Metropolitan Police warned that some protesters planned to "cause disorder".
The vigil is being staged in protest against what his family have branded a "perverse" inquest finding this week that Mr Duggan, 29, was lawfully killed by police.
Mr Duggan's mother Pamela and aunt Carole were joined by crowds carrying placards which read "Justice for Mark Duggan - 1476 deaths in custody or following police contact since 1990 not one conviction".
His death at the hands of a Metropolitan Police marksman sparked riots across the country in 2011.
Reggae and hip hop music was played from loud speakers as the family of Sean Rigg, a black musician who died in Brixton police station, joined the march.
Trade unionists were also present, while Tottenham Hotspur fans went past the protest to their home game against Crystal Palace at nearby White Hart Lane.
The crowd held a minute's silence before chanting "No justice, no peace".
Later they shouted: "Who are the murderers? Police are the murderers."
Carole Duggan told protesters: "The more we people come together and support each other, maybe we can make a better life for our children, for all of those children who have to live in these communities that are over-policed, where they are not free.
"They don't have the same freedom as other children in other parts of the country and that's not fair.
"What we have got to remember - Mark isn't here and we are doing this for his children.
"So let's show the country that we are not this gangster family that the media has been systematically portraying us as.
"Mark was not a gangster, the media sustained a campaign against him.
"We're just an ordinary family."
Mr Duggan's aunt later called for a new Independent Police Complaints Commission investigation (IPCC) into his death.
She said: "Mark did not get the justice he deserved from the inquest, so therefore we have no alternative but to go back to basics, start at the beginning.
"The beginning was with the IPCC - what we really want the IPCC to do now is what they should have done in the beginning and that is a thorough investigation.
"On numerous occasions during the IPCC investigation they were criticised, they were hauled up and they were accused of incompetence, which they admitted to, so it's nothing they don't already know.
"They know they're incompetent, they know they didn't do a thorough job because they were investigating their own people - 65% of IPCC members are ex-police, and I believe that's why Mark did not get the justice he should have got."
The Metropolitan Police said that extra officers were on standby to respond to any trouble and would take immediate action.
The statement said: "Today is a busy day in the Capital and we have a policing operation in place across London.
"This includes having additional officers on standby that could respond to any incident that occurs.
"Part of this operation includes assessing all available information and intelligence, and we are aware of a limited amount of information that indicates a small number of people are expressing their desire to use this vigil as an opportunity.
"This information includes the intention of protest groups to attend and of people looking to provoke disorder. We will be ready to intervene immediately if required."
The statement added: "The family has expressed that they wish this vigil to be held in a dignified and peaceful manner.
"The MPS has met with the organiser to ensure that we can appropriately facilitate their plans."
The police statement follows concerns that the crowds would clash with football fans going to see Tottenham Hotspur play Crystal Palace.
On Thursday Britain's most senior police officer and Prime Minister David Cameron both urged supporters to remain calm at the vigil.
The commissioner of the Metropolitan Police, Sir Bernard Hogan-Howe, thanked the Duggan family for their public calls for peace, and said: "A vigil is to commemorate Mark Duggan's death, that's what the vigil is about.
"It's a terrible tragedy that someone's lost a life in this case, and clearly the family want to register, I believe, their protest about the outcome of the inquest.
''They've got every right to do that, and we as the police have got every opportunity to facilitate that so that's exactly what we will do.
''We will continue to talk to the family and others to keep our communications alive, and also to make sure, as I believe, that the protest will happen and that there won't be disorder.''
Mr Duggan's aunt Carole said that she wanted "no more violence".
Unrest erupted after protests during the immediate aftermath of Mr Duggan's death in August 2011. He was shot dead by a police marksman after officers stopped the taxi in which he was travelling.
Police believed he was going to collect a gun from another man, Kevin Hutchinson-Foster, and then travel on to Broadwater Farm, also in Tottenham.
More than two years on, anger again spilled over at the Royal Courts of Justice on Wednesday, when an inquest jury found that he was lawfully killed.
They said it was most likely that he had a gun with him in the minicab, but had thrown it onto a nearby grass verge before he was shot.
Family and friends of the father-of-six shouted and swore, and his brother Marlon had to be physically restrained as the conclusions were read.
Outside the court, Assistant Commissioner Mark Rowley was drowned out by protesters shouting "murderers" and "scum" as he tried to make a statement on Scotland Yard's behalf.