The present invention relates to a pet bed that includes a heating layer which is formed of an enclosure and a heating composition sealed inside the enclosure. The enclosure includes a gas-permeable section such that the heating composition generates heat when a gas is received through the gas-permeable section. The pet bed further includes (i) a liner attached to the heating layer to engage a pet as the pet lies on the pet bed; (ii) a conforming layer attached to the heating layer such that the conforming layer conforms to the shape of the pet as the pet lies on the pet bed; and/or (iii) a backing layer attached to the heating layer such that the backing layer restricts movement of the pet bed. The enclosure may further include a cover over the gas-permeable section such that the heating composition generates heat when the cover is removed from the enclosure.