The legend of all the eleven temples of Thirunangur are closely associated with each other. As per legend, the Hindu god Shiva started dancing in fury at this place after the death of his consort Uma due to the yagna (sacrifice) of Daksha. Each time his lock of hair touched the ground, there were eleven other forms of Shiva who appeared.
The celestial deities were worried that if the dance continues, it would result in decimation of entire creations. They prayed to Vishnu for help, who appeared at this place. On seeing Vishnu, Shiva's anger was reduced and he requested Vishnu to appear in eleven forms like he did. On his request, Vishnu appeared in eleven different forms at Tirunangur.
The eleven places where Vishnu appeared are believed to be where the eleven temples in Tirunangur are located. As per another variant, Shiva requested Vishnu to appear in eleven different forms like him to control the eleven Shiva forms he created.The eleven Rudras, called Ekadas Rudras and king of devas, Indra, are believed to have worshiped Vishnu at this temple.
The presiding deity of Badrinath Temple, Badrinath, is believed to have visited the place on the request of Shiva. Ramanuja is believed to have learnt Tirumandiram from Thirukoshtiyur Nambi at this place.
The temple is revered in Nalayira Divya Prabhandam, the 7th–9th century Vaishnava canon, by Periazhwar, Thirumalisai Alvar and Thirumangai Azhwar. The temple is classified as a Divyadesam, one of the 108 Vishnu temples that are mentioned in the book. During the 18th and 19th centuries, the temple finds mention in several works like 108 Tirupathi Anthathi by Divya Kavi Pillai Perumal Aiyangar.
It is believed that saint Thirumanagai Azhwar visits the place every year to the festival to consecrate the eleven deities. As per local beliefs, the fresh winds which swirl the paddy fields before the day of the festival indicates a good harvest for the season. As per the accounts provided by the Azhawar saints, the place was called Thirumanimadam on account of the rich houses in the locality which had balconies.
As per another legend, the sages Madangar, Domyar, Vyagrapadar and Udangar set up their hermitages in this place. During the period of Mahabharatha, Datsagan, the mighty snake king who killed king Parikshit, ruled the place called Nagapuri, which eventually became Nangur.