Once a king by name Sumati, who was a staunch devotee of Lord Vishnu, yearned to have darshan of Sri Parthasarathi, the divine charioteer of Arjuna. Lord Vishnu in a dream directed him to go to Vrindaranya and meditate upon him. Meanwhile, Vedavyasa blessed sage Atreya with a sacred idol of Lord Vishnu with Panchajanyam (Shanku or conch) in His left hand and in the Gnanamudra posture. He brought the idol to Vrindaranya and handed it over to king Sumati. The king built a proper shrine and consecrated the idol of Lord Parthasarathi.
According to another legend, Atri Maharishi did penance in Vrindaranya to have darshan of Lord Narasimha. The sage, who was blessed with an image of Lord Narasimha, installed the idol here. Legend also has it that sage Brighu wished to have Devi Lakshmi as his daughter and came to Vrindaranya and lived near a lily pond here. With the passsage of time, the sage found a female child in a lily flower and named her Vedavalli. She is Devi Lakshmi incarnate. The sage brought her up with utmost care and love. As she grew up into a beautiful maiden, Lord Vishnu came in disguise and asked her hand in marriage. He is worshipped as Sri Ranganatha . Devi Lakshmi affectionately called Him Srimannathar.