It is believed that the idol in this temple is 5,000 years old and is worshipped by Lord Brahma at Dwaraka and was gifted to Lord Vishnu in his incarnation as Krishna. Legend statess that after Lord Krishna left for his heavenly abode, the holy city of Dwaraka was to be submerged. The instructor of the Devas, Guru Brihaspati and god of the winds, Vayu were asked to find a holy place for the idol. At the end of a long search for an appropriate site they entered Kerala and met Sree Parasurama, creator of Kerala. The idol was installed at this spot and called Guruvauurappan or the Lord of Guruvayur. Since Guru and Vayu installed the idol the place was called Guruvayurappa and later as Guruvayur.
The east facing temple has two gopurams or gateways on the east and west sides. The eastern gopuram is also called Bhooloka Vaikuntam and is the main entrance to the temple. In the middle of the inner courtyard is a pillared hall called 'Nalambalam' or 'Chutambalam' with scores of oil lamps adorning the walls. Inside the Chutambalam or outer enclosure is the square two-storeyed Sreekovil (main shrine) with three rooms. The innermost room has the sanctum sanctorum and the deity can be viewed from the temple entrance. This idol of Vishnu has four arms carrying a conch, a discus, the mace and a lotus and wears a tulasi (basil leaves) garland and pearl necklaces.
Seventeenth century paintings telling stories from Krishna’s life are all over the walls of the main shrine. The roof and the two doors are covered with gold. In the eastern side in front of the Chutambalam stands the tall 33.5 mt high gold plated dwajasthambam (flag post) and adjacent to it is a 7mt high dipastambham (pillar of lamps) whose thirteen circular receptacles look grand when lit.
The western gopuram has dipastambhams on either sides. There are also shrines to Goddess Durga (Edathidettukkaavu Bhagawati) in the north, Lord Ganapathy and Lord Ayyapan on the south side of Chutambalam. Only Hindus are allowed in the temple.