The Ottoman Turkish alphabet (Ottoman Turkish: الفبا, romanized: elifbâ) is a version of the Perso-Arabic script used to write Ottoman Turkish for over 600 years until 1928, when it was replaced by the Latin-based modern Turkish alphabet.

Though Ottoman Turkish was primarily written in this script, non-Muslim Ottoman subjects sometimes wrote it in other scripts, including Armenian, Greek, Latin and Hebrew alphabets.

The various Turkic languages have been written in a number of different alphabets, including Arabic, Cyrillic, Greek, Latin and other writing systems.

The earliest known Turkic alphabet is the Orkhon script. When Turks adopted Islam, they began to use Arabic script for their languages, especially under the Kara-Khanids. Though the Seljuks used Persian as their official language, in the late Seljuk period, Turkish began to be written again in Anatolia in the nascent Ottoman state.

The Ottoman Turkish alphabet is a form of the Perso-Arabic script that, despite not being able to differentiate O and U, was otherwise generally better suited to writing Turkic words rather than Perso-Arabic words. Turkic words had all of their vowels written in and had systematic spelling rules and seldom needed to be memorized. Other Oghuz Turkic languages such as Azerbaijani and Turkmen enjoyed a high degree of written mutual intelligibility as the Ottoman Alphabet catered to anachronistic Turkic consonants and spellings that demonstrated Anatolian Turkish' shared history with Azerbaijani and Turkmen. The Ottoman Turkish alphabet however was poorly suited to Arabic and Persian loanwords which needed to be memorized by students learning Turkish as it would omit vowels making them difficult to read. Arabic has several consonants that do not exist in Turkish, making several Arabic letters superfluous.

The introduction of the telegraph and the printing press in the 19th century exposed further weaknesses in the Arabic script.

Some Turkish reformers promoted the Latin script well before Atatürk's reforms. In 1862, during an earlier period of reform, the statesman Münif Pasha advocated a reform of the alphabet. At the start of the 20th century, similar proposals were made by several writers associated with the Young Turk movement, including Hüseyin Cahit, Abdullah Cevdet and Celâl Nuri. In 1917, Enver Pasha introduced a revised alphabet, the hurûf-ı munfasıla representing Turkish sounds more accurately; it was based on Arabic letter forms, but written separately, not joined cursively. It was for a time the official script of the Army.

The romanization issue was raised again in 1923 during the İzmir Economic Congress of the new Turkish Republic, sparking a public debate that was to continue for several years. A move away from the Arabic script was strongly opposed by conservative and religious elements. It was argued that romanization of the script would detach Turkey from the wider Islamic world, substituting a foreign (European) concept of national identity for the confessional community.