Police stop and search people during this year's Notting Hill Carnival (REUTERS)
As of 10.15pm on Monday, the Met Police said it made 240 arrests on Monday and 133 on Sunday, which included 10 made by the British Transport Police (BTP).
A further 12 arrests were carried out by BTP on Monday.
Officers detained 156 people on drugs offences, 69 on suspicion of possession of an offensive weapon and nine on suspicion of sexual offences.
Among the items seized were knives, a metal pole and a taser.
Notting Hill Carnival Day Two - In pictures
Police were operating with enhanced stop-and-search powers in a bid to crack down on violence.
Scotland Yard imposed a Section 60 order across the carnival area between 9am and 11.59pm. The order allowed officers to search people if they believed they were carrying offensive weapons or in anticipation of violence.
The bank holiday weekend event was policed by the highest number of officers in six years.
Almost 7,000, some from the Metropolitan Police's newly formed Violent Crime Task Force, policed Monday's event to "combat the threat of violent crime".
After a wave of violent crime in the capital in recent months, Scotland Yard announced knife arches had been placed at "strategic points" along the route to help reassure people about their safety, though officials did not disclose where.