The island's indigenous Sasak people are predominantly Muslim however before the arrival of Islam Lombok experienced a long period of Hindu and Buddhist influence that reached the island through Java. A minority Balinese Hindu culture remains in Lombok. Islam may have first been brought to Lombok by traders arriving from Sumbawa in the 17th century who then established a following in eastern Lombok. Other accounts describe the first influences arriving in the first half of the sixteenth century. According to the palm leaf manuscript Babad Lombok which contains the history of Lombok describes how Sunan Prapen was sent by his father The Susuhunan Ratu of Giri on a military expedition to Lombok and Sumbawa in order to convert the population and propagate the new religion. However, the new religion took on a highly syncretistic character, frequently mixing animist and Hindu-Buddhist beliefs and practices with Islam.

Hinduism is followed by ethnic Balinese and by a minority of the indigenous Sasak. All the main Hindu religious ceremonies are celebrated in Lombok and there are many villages throughout Lombok that have a Hindu majority population. According to local legends two of the oldest villages on the island, Bayan and Sembalun, were founded by a prince of Majapahit.

The Nagarakertagama, the 14th century palm leaf poem that was found on Lombok, places the island as one of the vassals of the Majapahit empire. This manuscript contained detailed descriptions of the Majapahit Kingdom and also affirmed the importance of Hindu-Buddhism in the Majapahit empire by describing temple, palaces and several ceremonial observances.

Christianity is practised by a small minority including some ethnic Chinese and immigrants from Bali and East Nusa Tenggara. There are Roman Catholic churches and parishes in Ampenan, Mataram, Praya and Tanjung. There is a catholic hospital in Mataram as well. Two Buddhist temples can be visited in and around Tanjung where about 800 Buddhists live.