An older system in the tradition of common Slavic scientific transliteration was adopted by the Council of Orthography and Transcription of Geographical Names in Sofia in 1972 and subsequently by the UN in 1977.

It was adopted in 1973 as the Bulgarian state standard BDS 1596:1973 which, although still valid formally[5] is no longer used in practice,[6] having been superseded by the 2009 Transliteration Act.

The second system was a French-oriented transliteration of personal and place names in the documents issued by the Bulgarian Ministry of Interior for travel abroad, used until 1999.

[7] Systems based on a radically different principle, which avoids diacritics and is optimized for compatibility with English sound-letter correspondences,[8] have come into official use in Bulgaria since the mid-1990s.

[15][16][17] In 2009, a law passed by the Bulgarian parliament made this system mandatory for all official use and some types of private publications, expanding also the application of the ia-exception rule to all -ия in word-final position.

The standard transliteration form of a given text is obtained from its unambiguously reversible one by simply removing the additional symbols ` (grave accent) and | (vertical bar).

[22] The ISO 9 standard, in its 1995 version, has introduced another romanization system that works with a consistent one-to-one reversible mapping, resorting to rare diacritic combinations such as ⟨â,û,ŝ⟩.

The archaic Cyrillic letters ѣ and ѫ, which were part of the pre-1945 orthography of Bulgarian, are variously transcribed as ⟨i͡e, e⟩, as ⟨ya, ě⟩, and as ⟨u̐, ŭǎ⟩, respectively, in the ALA/LC, BGN/PCGN and ISO 9 standards.