It was described as a result of a taxonomic split in the large-eared free-tailed bat, Otomops martiensseni.

The authors chose the species name "harrisoni" after the late mammalogist David L. Harrison.

Of Harrison, they wrote: "[his] numerous publications on Afro-Arabian Chiroptera, in particular the Molossidae, have significantly improved our knowledge of this poorly known family.

It can be differentiated from other members of its genus based on its long cranium and exceptionally high braincase.

On its back, the fur is dark chocolate brown; it has a "distinct cream-coloured collar" around its neck.

The edges of its body and of its wing membranes have a thin, but distinct, band of white fur.

Males and females both reach sexual maturity at around one year of age and a body mass of 25 g (0.88 oz).

Distribution modeling predicts that it prefers areas that receive at least 20 mm (0.79 in) of rain in the driest month, altitudes greater than 1,500 m (4,900 ft) above sea level, and locations with a total annual rainfall of less than 500 mm (20 in).