[6] The genus name Lanthanotus means "hidden ear" and the species name borneensis refers to its home island of Borneo.

In 1899, George Albert Boulenger relegated it to the family Helodermatidae, together with the beaded lizards and Gila monster, on the basis of morphological similarities.

[8] More recent genetic evidence has found that the nearest relative of the earless monitor lizard is Varanidae.

[9][10] Most authorities continue to recognize them as separate families as the divergence between them is deep,[6][9][10] but some have suggested that the earless monitor lizard should be included as a subfamily, Lanthanotinae, of the Varanidae.

[5][12] The extinct Cherminotus known from Late Cretaceous fossil remains in Mongolia has been considered a member of Lanthanotidae, but this is disputed.

[13] The earless monitor lizard is endemic to the Southeast Asian island of Borneo, where it is known from Sarawak in East Malaysia, as well as West and North Kalimantan in Indonesia.

[20][21] These are typically in rainforests, but it is also found in streams flowing through degraded habitats such as agricultural land, mature fruit tree gardens and palm oil plantations, and reportedly may occur in rice paddies.

[4][25] The upperparts are orangish-brown, and the underside is mottled dark brown and whitish, pale yellowish, ochre or rusty.

[31] Earless monitor lizards are generally strictly nocturnal animals, although exceptional daytime observations in the open have been reported.

[5][20] They are generally quite inactive and not agile, but can make surprisingly fast spurts when startled,[16] and will rapidly catch prey items placed in front of them.

[16] In captivity they sometimes remain virtually immobile underwater for hours, periodically lifting the nose above the water's surface to breathe.

[16] It has been speculated that the prehensile tail is wrapped around stones, roots and other things underwater to avoid being swept along during floods.

[34] The main components are kallikreins (to a lesser degree CRiSP) with the primary effect being the cleaving of fibrinogen, which is important for blood clotting.

[20] In captivity, they will eat fish (both whole and pieces), earthworms, squid, shrimp, tadpoles, yolk from green sea turtle eggs, pieces of pig and chicken liver, baby mice and mussels, but refuse to take bird eggs and legs of frog.

[4] Based on captive observations a pair will mate repeatedly over a period of a few months, with each session lasting for hours.

[16] Despite this high density in a stream used by locals for washing, fishing and as a source of drinking water, they only reported seeing the species very rarely and some had never seen it.

[7] These were generally collected in the 1960s–1980s or earlier,[15] often during floods when earless monitor lizards were swept along the current and ended up in fishing traps.

[28] In 2012 it was featured in a Japanese reptile keepers magazine and in the following years a larger number of individuals entered captivity.

[40] Collecting the species from the wild is illegal; the earless monitor lizard has been protected in Malaysia since 1971, in Brunei since 1978 and in Indonesia since 1980.

[40] As a precaution some scientists that have discovered individuals in the wild have refused to provide the exact location, only describing it in very broad terms, citing fears of alerting wildlife traders.

[21] Habitat loss represents another serious threat, as forests in Borneo rapidly are being replaced by oil palm plantations.