Idols of Hindu gods were immersed in the river Thames in west London, as hundreds from the Hindu Bengali community attended the ceremony.
The idols are made of clay, straw and organic vegetable dyes
This is the first time the community was allowed to give a traditional send-off to the deities by London's port authorities.
The idols, belonging to a tableau measuring 18ft by 20ft, were made from clay, straw and vegetable dyes.
The submergence marked the end of the week-long festival of Durga Puja.
The installation - comprising of the main female goddess Durga, the demon she is depicted slaughtering and her children - were built at the British Museum by craftsmen who were brought in from the Indian state of West Bengal.
The idols were then moved to the Camden Town Hall where the week-long festival was held.
The idols were dismantled and taken to a slipway near Putney Bridge, accompanied by music from traditional drummers.
A priest first conducted the ritual of "purification" of the Thames by sprinkling some water from the river Ganges, which has been brought from India.
The idols were then carried to the water, to be washed away by the high tide later.
Port authorities set up special nets to catch residues - the clothes, the bamboo and straw structure - once the sculptures dissolved.
The organisers, London Durga Puja Dusserah Committee, said this is the first time in its 40 year history the community had got a chance to observe all the rituals.
"This is a very sentimental issue for us, everybody wanted to see the idols being given a proper immersion," Shyamal Mukherjee, the general secretary of the committee, said.
Many curious onlookers who saw the ceremony from the Putney Bridge said they were enthralled by the "unusual but lively and colourful" event.
Usually, the idols - much smaller in scale - are made in India and then shipped here for the festival.
After the festival the tableau is dismantled and stored in warehouses to be recycled and worshipped for the next four or five years.