O with diaeresis is used in the alphabets of the Altai, Khanty, Khakas, Komi, Kurdish, Mari, Shor and Udmurt languages.

In Altai, Khakas, Khanty and Shor, it represents the close-mid front rounded vowel /ø/, like the pronunciation of the ⟨ir⟩ in "bird" in non-rhotic dialects of English.

In Kurdish, it represents the near-close near-back rounded vowel /ʊ/, like the ⟨oo⟩ in "book".

In Russian books until the beginning of the 20th century, the letter Ӧ has been sporadically used instead of Ё in foreign names and loanwords (for example, the city of Cologne, Germany, which is Köln in German, might have been rendered in Russian as "Кӧльн").

[1] In Tatar, this letter appeared in the 1861 Cyrillic orthography by Nikolay Ilminsky.