Thrissur Pooram (തൃശ്ശൂര്‍ പൂരം) was the brainchild of Sakthan Thampuran, the Maharaja of Cochin (1790–1805).^{[citation needed]} Before the start of Thrissur Pooram, the largest temple festival in Kerala was the one-day festival held at Aarattupuzha known as Arattupuzha Pooram. Temples in and around the city of Thrissur were regular participants. In the year 1798 because of incessant rains, the temples from Thrissur were late for the Arattupuzha Pooram and were denied access to the Pooram procession. Feeling embarrassed and angered by the denial, the temple authorities raised the issue with Sakthan Thampuran.

This made him take the decision to unify the 10 temples situated around Vadakkunnathan Temple and organized the celebration of Thrissur Pooram as a mass festival. He invited temples with their deities to the city of Thrissur to pay obeisance to Vadakkunnathan (Shiva), the presiding deity of the Vadakkunnathan Temple. Something unique about this festival is that everything used in the festival is made fresh every year from scratch.