The annual chariot festival at the famous Viswanathaswamy Temple at Kalpathy is held in the month of November. Kalpathy is one of the ancient Brahmin Agraharam (traditional house). Also known as Kalpathy Ratholsavam or Kalpathy Theru festival, the festival is based on Vedic Tamil Brahmin culture which lasts for seven days.

The main attraction of the festival are the six magnificent chariots (three from the Viswanathaswamy Temple and three from the nearby temples of Manthakkara Maha Ganapathy, Lakshminarayana Perumal of Old Kalpathy, and Maha Ganapathy of Chathapuram) beautifully decorated with flowers, flags, sugarcane, coconuts etc are ceremoniously drawn through the streets by thousands of devotees. The procession is accompanied by caparisoned elephants and percussion. It is believed that pulling the chariots will wash off all the sins for a lot of generations.

Three satellite temples of the Viswanathaswamy Temple in the villages of new Kalpathy, old Kalpathy and Chathapuram also celebrate this festival.