The Urdu alphabet (Urdu: اُردُو حُرُوفِ تَہَجِّی‌, romanized: urdū ḥurūf-i tahajjī) is the right-to-left alphabet used for writing Urdu. It is a modification of the Persian alphabet, which itself is derived from the Arabic script. It has co-official status in the republics of Pakistan, India and South Africa. The Urdu alphabet has up to 39 or 40 distinct letters with no distinct letter cases and is typically written in the calligraphic Nastaʿlīq script, whereas Arabic is more commonly written in the Naskh style.

Usually, bare transliterations of Urdu into the Latin alphabet (called Roman Urdu) omit many phonemic elements that have no equivalent in English or other languages commonly written in the Latin script.

The standard Urdu script is a modified version of the Perso-Arabic script and has its origins in the 13th century Iran. It is also related to Shahmukhi, used for the Punjabi language varieties in Punjab, Pakistan. It is closely related to the development of the Nastaʻliq style of Perso-Arabic script. During the Mughal era, Nasta'liq became the common script for writing the Hindustani language, especially Urdu.

Despite the invention of the Urdu typewriter in 1911, Urdu newspapers continued to publish prints of handwritten scripts by calligraphers known as katibs or khush-navees until the late 1980s. The Pakistani national newspaper Daily Jang was the first Urdu newspaper to use Nastaʿlīq computer-based composition. There are efforts under way to develop more sophisticated and user-friendly Urdu support on computers and the internet. Nowadays, nearly all Urdu newspapers, magazines, journals, and periodicals are composed on computers with Urdu software programs.

Other than the Indian subcontinent, the Urdu script is also used by Pakistan's large diaspora, including in the United Kingdom, the United Arab Emirates, the United States, Canada, Saudi Arabia and other places.

Urdu is written in the Nastaliq style (Persian: نستعلیق Nastaʿlīq). The Nastaliq calligraphic writing style began as a Persian mixture of the Naskh and Ta'liq scripts. After the Muslim conquest of the Indian subcontinent, Nastaʻliq became the preferred writing style for Urdu. It is the dominant style in Pakistan and many Urdu writers elsewhere in the world use it. Nastaʿlīq is more cursive and flowing than its Naskh counterpart.

In the Arabic alphabet, and many others derived from it, letters are regarded as having two or three general forms each, based on their position in the word (though Arabic calligraphy can add a great deal of complexity). But the Nastaliq style in which Urdu is written uses more than three general forms for many letters, even in simple non-decorative documents.

The Urdu script is an abjad script derived from the modern Persian script, which is itself a derivative of the Arabic script. As an abjad, the Urdu script only shows consonants and long vowels; short vowels can only be inferred by the consonants' relation to each other. While this type of script is convenient in Semitic languages like Arabic and Hebrew, whose consonant roots are the key of the sentence, Urdu is an Indo-European language, which requires more precision in vowel sound pronunciation, hence necessitating more memorisation. The number of letters in the Urdu alphabet is somewhat ambiguous and debated.