Religion in Kerala is diverse. According to 2011 census of India figures, 54.73% of Kerala's population follows Hinduism, 26.56% are followers of Islam, 18.38% follow Christianity, and the remaining 0.33% follow other religions or have no religion.

The historical legends regarding the origin of Kerala are Hindu in nature. Kerala produced several saints and movements. Adi Shankara was a religious philosopher who contributed to Hinduism and propagated the philosophy of Advaita. Hindus represent the biggest religious group in all districts except Malappuram, where they are outnumbered by Muslims. Various tribal people in Kerala have retained the religious beliefs of their ancestors.

Hinduism is the most widely professed faith in Kerala. According to 2011 Census of India figures, 54.7% of Kerala's residents are Hindus. Hindus represent the biggest religious group in all districts except Malappuram.

Kerala produced several saints and movements. Adi Shankara was a religious philosopher who contributed to Hinduism and propagated the philosophy of Advaita. He was instrumental in establishing four mathas at Sringeri, Dwarka, Puri and Jyotirmath. Melpathur Narayana Bhattathiri was another religious figure who composed Narayaniyam, a collection of verses in praise of the Hindu God Krishna.

Various practises of Hinduism are unique to Kerala. Worship of Shiva and Vishnu is popular in Kerala. Lord Krishna is worshipped widely in all parts of Kerala, Guruvayur being one of the most famous temples in the state. Malayali Hindus also worship Bhagavathi as a form of Shakti. Almost every village in Kerala has a Bhagavati Goddess. Hindus in Kerala also strongly believe in power of snake gods and usually have sacred snake groves known as Sarpa Kavu near to their houses.

Some of the most notable temples are:Thiruvananthapuram Padmanabhaswamy Temple, Thiruvallam Sree Parasurama Swami Temple, Janardhanaswamy Temple, Vellayani Devi Temple, Pazhaya Sreekanteswaram Temple, Ananthapura Lake Temple, Sabarimala Ayyappa Temple, Angadipuram Thirumandhamkunnu Temple, Alathiyoor Hanuman Temple, Bhayankavu Bhagavathi Temple, Kadampuzha Devi Temple, Keraladeshpuram Temple, Panniyur Sri Varahamurthy Temple, Sukapuram Dakshinamoorthy Temple, Thirunavaya Navamukunda Temple, Triprangode Siva Temple, Tali Shiva Temple, Trikkandiyur Siva Temple, Thrissur Vadakkunnathan Temple, Guruvayur Temple, Thriprayar Temple, Lokanarkavu Temple, Thirunelli Temple, Aranmula Parthasarathy Temple, Chottanikkara Temple, Chengannur Mahadeva Temple, Parassinikadavu Muthappan Temple, Chettikulangara Devi Temple, Mannarasala Temple, Chakkulathukavu Temple, Thiruvalla Sreevallabha Temple, Kaviyoor Mahadevar Temple, Parumala Panayannarkavu Temple, Sree Poornathrayesa Temple, Kodungallur Bhagavathy Temple, Trikkur Mahadeva Temple, Manalarkavu Devi Temple and Rajarajeshwara Temple. Temples in Kerala follow elaborate rituals and traditionally only priests from the Nambudiri caste could be appointed as priests in major temples. But in 2017 as per the state government's decision, the priests from the historically backward caste communities are now being appointed as priests.

Malayali Hindus practice ceremonies such as Chorunu (first feeding of rice to a child) and Vidyāraṃbhaṃ.

Kerala has been a major spice exporter since 3000 BCE, according to Sumerian records and it is still referred to as the "Garden of Spices" or as the "Spice Garden of India". Kerala's spices attracted ancient Arabs, Babylonians, Assyrians and Egyptians to the Malabar Coast in the 3rd and 2nd millennia BCE. Phoenicians established trade with Kerala during this period. Arabs and Phoenicians were the first to enter Malabar Coast to trade Spices. The Arabs on the coasts of Yemen, Oman, and the Persian Gulf, must have made the first long voyage to Kerala and other eastern countries. They must have brought the Cinnamon of Kerala to the Middle East. The Greek historian Herodotus (5th century BCE) records that in his time the cinnamon spice industry was monopolized by the Egyptians and the Phoenicians.