By the Bhagavatam, it is believed that Shiva fell in love with Vishnu when he was in the form of Mohini. Their connection resulted in the birth of a child named Shasta, who was also known as Hariharaputra since Shiva is also known as Hara and Vishnu as Hari. Ayyappa is believed to be an incarnation of Shasta. The worship of Shasta has been a part of the ancient history of South India, and many Shasta temples can be found in South India and across the world. Five Shasta temples are said to be linked to Parashurama, an incarnation of Vishnu. These include the Sastha temples in Kulathupuzha, Aryankavu, Achankovil, Sabarimala, and Ponnambalmedu. According to folklore, the temple in Kulathupuzha is related to the deity's childhood years, where he was enshrined as a child. The Aryankavu temple is related to the deity's adolescence, the Brahmachari state. The Achankovil temple is connected to the deity's Grahastha years, where he is shown sitting on a horse and holding a sword, along with his wives, Pushkala and Poorna. The Sabarimala temple is associated with the deity's Vanaprastha years, and in the Ponnambalmedu or Kantamala temple, the deity is shown as the greatest Yogi.

In 1950, the temple was reconstructed after an arson attack. No charges were filed, and the previous stone image of the deity was replaced with a 1.5-foot-tall panchaloha (an alloy of five metals) idol. The Panchaloha idol was created by Neelakanta Panicker and his younger brother, Ayyappa Panicker, who are members of the Thattavila Vishwakarma family in Chengannur, Kerala. The supervisor in charge of the new idol was Edavankadan T.N. Padmanabhan Achari from Mavaelikkara, who was appointed by Maharaja Sree Chithira Tirunaal Balarama Varma. In the early 1950s, the present panchaloha idol of Ayyappan was installed at Sabarimalai, and a procession was taken throughout the Madras state, thanks to P. T. Rajan's efforts.