[2][3][4] It is endemic to Kenya and only know from the vicinity of its type locality, Ngaia Forest Reserve, in the Nyambene Hills, Meru County;[2] the type locality is also spelled "Ngaya" or "Ngaja".

The specific name spawlsi honours Stephen Spawls who first collected this species and who has contributed substantially to African herpetology.

[1][2][3] The first specimen was collected in the Nyambene Hills in 2007 and was considered most similar to Boulengerula denhardti.

[1] Boulengerula spawlsi is known from the Ngaia Forest Reserve at elevations of 1,300–1,419 m (4,265–4,656 ft) above sea level.

Specimens have been dug from soil in a hollowed-out base of the trunk of a large fallen tree, under stones and rotting logs, or found in leaf-litter debris.