Although the otherkin community is a diverse and loosely defined one and lacks an explicit ideology, some beliefs are especially common. Otherkin tend to have a number of New Age sensibilities and to be very open to supernatural concepts, particularly belief in the soul or spirit. Other common beliefs in the otherkin community include animism, Neo-Paganism, totemism, possession, reincarnation, and other paranormal events.

Some hold these beliefs not as a search for the truth, but as a way to help understand and explore themselves. Indeed, as the community has expanded and become more self-analytical in recent years, a number of otherkin have begun explaining their association with non-human imagery as nothing but an exercise to help become in touch with their true selves.

Most otherkin believe they have non-human aspects that are either spiritual or philosophical in nature. According to otherkin.net some claim that they are human in a physical sense but non-human ("other") in a mental or spiritual one. Some otherkin attribute this discrepancy to reincarnation or a soul for another species incarnated as a human.

There are also otherkin who believe themselves to be biologically non-human who consider themselves to be physically members of the species they associate themselves with, or at least directly descended from the species through intermarriage with humanity. This belief is rarer within the subculture and sometimes the subject of criticism from otherkin who do not share it.  Some otherkin who do not necessarily claim that they are genetically non-human do profess to have non-human sides that have somehow influenced their physical bodies, according to otherkin.net.

Some otherkin claim to be combinations of different non-human species, such as elf-werewolf or dragon-cat hybrids. Others believe that they are able to mentally or astrally change between different types of nonhuman beings or even that all otherkin are capable of this.

Some members of the otherkin subculture have drawn parallels between their beliefs and transsexuality, resulting in the neologism trans-speciesism, the conviction that one is in a body of the wrong species.

Despite the general conviction in the community that otherkin are born, not made, there is no clear definition of what constitutes otherness. One effect of this is that anyone who asserts mainstream otherkin status is very unlikely to be contradicted by the community itself, though more specific claims, or attempts to ascribe specific qualities to all otherkin, are more likely to meet opposition.