In Russian, it is pronounced [jɵ], with an [ɵ] vowel similar to bird in New Zealand or South African English; see palatalization for some background.

Yo occurs as a discrete letter in the Cyrillic alphabets of Belarusian, Rusyn, Mongolian and many Caucasian and Turkic languages.

Unstressed ⟨ё⟩ appears only in rare loanwords, in compound words (in this case it may be considered to have secondary stress; most notably, ⟨ё⟩ occurs in words containing the prefixes трёх- 'three-' and четырёх- 'four-'), in derivatives of the name of the letter ⟨ё⟩ itself (ёфика́тор - yoficator), in loanwords (кёнигсбе́ргский - adjective from Königsberg, сёрфинги́ст from surfing - surfer, сёдзё - shōjo, гёмбёц - gömböc).

[a] For examples, compare лёт [lʲɵt]ⓘ ("flight") from *letъ[1] in contrast to лещ [lʲeɕː]ⓘ ("bream") from *leščь;[1] or осётр [ɐˈsʲɵtr] ("sturgeon") from *esetr[2] in contrast to осeть [ɐˈsʲetʲ] ("granary, rack for drying grain") from *esetь.

For a long time, no distinction was made in written Russian between the vowels /e/ and /o/ after /j/ or after a palatalized (soft) consonant.

This digraph and a new letter ⟨ґ⟩ for the sound /ɡ/ were proposed as additions to the official alphabet in 1783 at a session of the Russian Academy under the presidency of Princess Yekaterina Romanovna Vorontsova-Dashkova, but both propositions were rejected by the academicians and the Metropolitan of Novgorod and Saint Petersburg Gavriil.

At that time, the sounds /jo/—/ʲo/ and /ɡ/ were common in everyday Central Russian speech, but Church-Slavonic-styled pronunciation with /je/–/ʲe/ and /ɣ/ was preferred when reading literary texts.

In 1797, instead of existing options, the letter "Ё" was created by Russian Imperial historian, writer, poet and critic Nikolay Mikhailovich Karamzin.

It was used for the first time in the 2nd book of "Aonides" in his poem "Sophistiated Solomon's Wisdom, or Thoughts Selected from Ecclesiastes" to create a rhyme between the words слёзы [ˈslʲɵzɨ] and розы [ˈrozɨ].

Otherwise, ⟨е⟩ is used, and ⟨ё⟩ occurs only when it is necessary to avoid ambiguity (such as to distinguish between все ("everybody") and всё ("everything") when it is not obvious from the context) or in words (principally proper nouns) whose pronunciation may not be familiar to the reader.

Recent recommendations (2006) from the Russian Language Institute are to use ⟨ё⟩ in proper nouns to avoid an incorrect pronunciation.

This letter is also often used for transcribing the English vowel /ɜr/, in names like Роберт Бёрнс for "Robert Burns" or Хёрст for "Hearst"/"Hurst"/"Hirst".

However, the sound [jo], in words from European languages, is normally transcribed into Russian as ⟨йо⟩ in initial and post-vocalic position and ⟨ьo⟩ after consonants: Нью-Йорк for "New York" and батальон for "battalion".

It is common for a person who has one of these surnames to possess some legal documents (passports, identification cards, marriage and birth certificates, property ownership papers, etc.)

On occasion such mismatches caused problems to citizens who receive inheritance or complete property transactions.

In modern Ukrainian spelling, the sound /jo/—/ʲo/ is written as ⟨ьо⟩ after soft consonants in the middle of words (such as "нього", "him" after a preposition), and ⟨йо⟩ elsewhere (such as "його", "him").