Turkish was written in the Arabic alphabet for several hundred years and Ottoman Turkish blended a great amount of Arabic and Persian vocabulary with Turkish words.
The current 29-letter Turkish alphabet was the personal initiative of the founder of the Turkish Republic, Mustafa Kemal Atatürk. It was one of the major revolutionary changes which came with Atatürk’s reforms after the birth of the Turkish Republic in 1923.
The Arabic alphabet was not well suited to Turkish because it was difficult to represent all the Turkish vowel sounds without adding more letters or diacritics. Even the Latin alphabet wasn’t enough which is why there are three accented vowels in the Turkish alphabet.
The transition to the Latin alphabet was formalised with a law passed on 1 November 1928, making the use of the new Turkish alphabet compulsory in all public communications and the education system, where it’s still mandatory today.