Officers seized a gun, gaffer tape and gloves as they raided a property in east London.
The swoop in Tower Hamlets was instigated in the run-up to the Notting Hill Carnival, which kicks off on August 29.
And it formed part of a London-wide operation which saw 1,000 officers arrest 62 people, mainly for charges including possession with intent to supply as well as violent offences.
Some included assault on police and public order offences.
They also recovered drugs and cash and targeted gangs they believed could pose a threat at the lively event.
The Met’s Notting Hill Carnival spokesman Supt Robyn Williams said: “Troublemakers are not welcome.
“The operation was aimed at making sure those who intend to cause trouble are prohibited.”
Officers trained as “super recognisers” will be in the carnival’s CCTV control room from Saturday to Bank Holiday Monday, searching for anyone banned from the event.