Scotland Yard’s gangs database is under investigation from the data watchdog after Amnesty International said it breaches international human rights law.
The secret database contains the details of 3,800 people, 40% of whom have a zero score for risk of violence.
Amnesty’s UK Director Kate Allen said: "There is clearly a huge problem with knife crime violence at the moment in London, but the Gangs Matrix is not the answer.
“It's part of an unhelpful and racialised focus on the concept of gangs. Put simply, it's the wrong tool for the wrong problem.
"The entire system is racially discriminatory, stigmatising young black men for the type of music they listen to or their social media behaviour, and perpetuating racial bias with potential impacts in all sorts of areas of their lives.
"Some police officers have been acting like they're in the wild west, making the false assumptions that they can set up fake profiles and covertly befriend people online to monitor them without needing the appropriate search warrants.
"The Mayor of London needs to dismantle the Matrix unless he can bring it in line with international human rights standards."
Amnesty found that the number of black men on the Matrix is disproportionate. Figures from July 2016 showed that 87% of the people listed were black, Asian and minority ethnic, and 78% were black.
For London as a whole, 13% of the population is black, and police figures show 27% of those prosecuted for youth violence are black.
In terms of age, 80% of those on the database were between the ages of 12 and 24, and 15% were minors, the youngest of whom was 12 years old. Males accounted for 99%.
The report claimed being on the Matrix could affect access to services such as housing, education and the job centre.
Amnesty has called on the Information Commissioner's Office (ICO) to examine whether the database breaks data and human rights laws, and has also called the Commons Home Affairs Select Committee to investigate the use of police gang databases across the country.
It is understood that officers in Nottingham, Manchester and Birmingham gather similar information on gang links.
Scotland Yard issued a statement that continued: "Some young people identified as part of a gang may not yet have been drawn into gang violence. These individuals will be offered support to divert them away from activity that may result in either violent offending or them becoming a victim.
"The scoring system on the matrix is subject to specific timescales, which means nominals convicted or linked to violence can score zero outside of these timescales.
“A number of those with a zero score may also be in custody therefore not currently offending.
"The style of music that someone listens to has no bearing on whether someone is placed on the matrix.
“However, evidence that someone is glorifying gang violence in a music video posted on social media can be used as an intelligence source.”
There are no "clear processes" for reviewing or updating the database, or challenging the inclusion of a name, and no definitive list of who is allowed access to the information, it said.
The Matrix was set up in 2012 in the wake of the wave of rioting that hit London and several other parts of the UK in the summer of 2011.