Revellers gathered to dance, drink and eat jerk chicken as samba and reggae beats blasted out over the suburb, turning the normally gentile neighbourhood into a raucous street party.
Exotic dancers in sequins and traditional steel drum bands paraded alongside brightly coloured floats making their way along the 3.5-mile (5.6-kilometre) route.
"Nobody's holding back, it's pretty lively, everyone's enjoying the sun and having a cracking time," said Gina Lyons, 24, from Brisbane in Australia.
With hundreds of police patrolling the streets, officials said the two-day party passed off peacefully, despite a string of arrests for low-level offences.
Police estimated the turnout at 500,000, more than double the number who gathered for the children's parade on Sunday, as people took advantage of warm weather on a public holiday.
"Yesterday we were really pleased from a policing perspective, (and) crime levels seem to be down from the same time last year and the arrests are down," said Chief Inspector Jo Edwards.
The mood was good-natured and family-friendly as large numbers of children accompanied their grandparents around the street stalls.
Residents, often with a bottle of wine in hand, watched from balcony windows as the carnival passed below.
Carnival began the 1950s in response to deteriorating race relations, and has been based in Notting Hill since 1964, a chance for London's Afro-Caribbean communities to celebrate their culture and traditions.
The event was marred by race riots in the past but in recent years has been viewed as a showcase for the British capital's mix of cultures.
There has been some opposition from local residents, but for most people, carnival -- held on a bank holiday weekend every August -- is a chance to let their hair down in one enormous free party.
Police maintain a visible presence, in particular to clamp down on anyone carrying knives or guns. By late Monday 133 people had been arrested, many for possession of drugs