The 158 suspected members were picked up in more than 300 raids across the city which started at dawn as hundreds of Metropolitan Police officers took to the streets.
Those detained are accused of assault, robbery, the supply of drugs and money laundering, police said, and officers seized "significant amounts of crack cocaine, heroin and cash".
The 1,000-strong Trident Gang Crime Command has been created to monitor gang activity and work with local authorities in London.
The unit, thought to be the largest in the country, has 19 dedicated gang crime task forces.
The Metropolitan Police Service said in a statement: "As part of the MPS crackdown on gang crime, 144 warrants have been executed so far across London, resulting in 158 arrests for a variety of offences including possession of a firearm, the supply and possession of drugs, money laundering and gang-related violence.
"A significant amount of cocaine and cannabis has been seized at various addresses across the capital."
Two people were arrested in Barnet in north London on suspicion of possession of a firearm, and a handgun found at the scene. Two rounds of ammunition and £4,000 ($6,350, 4,800 euros) were also seized.
A total of £10,000 was found at another address in London.
Violence and looting ripped through London in August, sparked by the death of a man in a police shooting in the northern district of Tottenham.
The unrest spread across the capital and then across England to the cities of Birmingham, where three men were killed, and Manchester.
In London alone, police have arrested nearly 3,900 people over the riots and of that figure, 2,385 have been charged or summonsed.