This is the least known rhinolophid species in Europe, and is therefore listed in the EUROBATS Meeting of Parties Resolution 9.3 as a Priority Species for autoecological studies. The scarce ecological information is reviewed in Bücs and Csorba (2022), who identified the species as typically dwelling in landscape mosaics of open habitats and shrubland, hunting in oak and hornbeam woodland, or along hedges, and, at least in Europe, feeding on moths. It roosts year-round in caves or artificial underground habitats. It is a sedentary species according to Hutterer et al. (2005).

In Europe, Rhinolophus blasii has the smallest range of all rhinolophids occurring in the continent and is the rarest of them (Bücs and Csorba 2022). Its European range (reviewed in Bücs and Csorba 2022, from which the following information is taken) is extremely patchy, mostly confined to karstic areas of the Balkan Peninsula, and spans from the westernmost records in Croatia to the easternmost in Bulgaria and Türkiye. It also occurs on large islands such as Crete and Cyprus and some small islands of the eastern Mediterranean but no longer occurs on Malta (not mapped). It is also Extinct (not mapped) in Italy (where it was restricted to the north-east karstic region) and Slovenia. It seems to be more frequent from west to east, and from north to south, with the largest population size in Bulgaria and Greece. Recently rediscovered in Romania, where its presence was uncertain. Taking European data altogether, the species is extremely rare, being identified in no more than 200 sites. The range of altitudes where this species can be found varies between 0 and 1,665 m asl.

Outside Europe, it occurs in Africa (from north-eastern South Africa and the Democratic Republic of Congo to Ethiopia, Somalia, and north-western Africa), patchily in Asia from Türkiye in the west, east to Pakistan, and from the Caucasus in the north to Yemen in the south (Simmons 2005).

It is protected by national legislation in some range states. There are international legal obligations for the protection of this species through the Eurobats Agreement and Bern Convention. It is included in Annexes II and IV of the EU/92/43 Habitats Directive and hence requires specific conservation measures, including the designation of Special Areas for Conservation. According to the 2013-2018 art. 17 reporting made under such Directive, the species has inadequate-unfavourable conservation status in all biogeographic regions where it occurs except the Alpine Region, where the status is classified as unknown. There are 102 Natura 2000 Sites designated in the EU to protect this species. There is an urgent need to provide reliable population estimates, counts being often impaired by the confusion made with morphologically similar species, as well as to carry out detailed habitat assessment studies. Besides, further research on habitat preferences in this species is needed to plan appropriate conservation measures.