Koorathalvan was born as Kuresan in a small hamlet 'Kooram' near Kanchi, in the year of 1010 A.D in an affluent family.
A bond was established between them and under the effective guidance of Ramanuja, Kuresan was initiated into the rigorous study of Vedic scriptures and other canons.
According to popular tradition, Varadaraja Perumal and his consort Perundevi heard the heavy sound of a door being closed.
Kuresan had closed the brass doors of his home, after completing his daily routine of feeding the poor.
On hearing this news, rather than feeling happy, Kuresan was extremely saddened, as he believed that it was a sin on his part to disturb the deity and his consort during the night by 'announcing' his charity activities.
Kuresan became a disciple of Ramanuja and assisted him in all his works such as spiritual study, management of the temple, philosophical compositions and many others.
Ramanujacharya and Koorathalvan, along with other disciples, undertook the tedious journey to Kashmir and met the king of that state.
With a great sense of fulfillment, Ramanuja completed the Sri Bashya, which was a commentary on the Brahmasutras.
The reason for his vengeance towards Vaishnavas was due to the Govindaraja Swamy idol present in Chidambaram.
The feet of Govindaraja reclining in the snake Adisesha were directed towards Lord Nataraja, which Kulothunga felt was an insult to his Shiva.
An elderly woman who attempted to visit Govindaraja was severely beheaded in broad daylight by the zealous Kulothunga himself.
Realising that this was a threat, Koorathalvan immediately rushed back to the ashram in Srirangam and requested Ramanuja and the others to move away to a safer place.
Ramanuja, meanwhile, had moved to Melkote in Karnataka along with his disciples and established Vaishnavism there with the support of the local king.
Koorathalvan did so, it is traditionally believed that God readily granted his eyes on the Kachi street of Kanchipuram.
For this reason, Vedanta Desikan hailed Lord Varadarajan as "Kachi thanil kan kodukkum perumal" (The deity who is the bestower of eyes).