The Mosque of Umar ibn al-Khattab (Arabic: مسجد عمر بن الخطاب) is a mosque located within the historic city of Dumat al-Jandal in the Al Jawf Province of Saudi Arabia. The mosque is named after the Rashidun caliph Umar ibn al-Khattab, who is believed to have constructed the mosque, although this claim has been contested. The mosque's minaret is the first of its kind to be built in North Arabia as well.

Adjacent to the mosque is the historic Marid Castle which dates back to around the 1st century CE.

The mosque was built during the reign of the Umayyad Caliphate. The Islamic tradition reports that Umar ibn al-Khattab built the mosque to pray at, while on his journey to Jerusalem, hence the mosque's name. However, the structure of the mosque does not resemble architecture contemporary to the time period of the Rashidun Caliphate, so the attribution of its construction to Umar is considered by some historians to be unreliable.

In 1793, the Saud family renovated the mosque, as well as rebuilt the prayer hall so that it faced the qibla in a more accurate direction. The mosque itself is still a popular tourist destination in the modern age.

The spiral, pyramidal-base minaret of the mosque is considered the oldest minaret in the whole of North Arabia. As for the mosque, the whole structure including the prayer hall and minaret are made out of brick.

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  Inside the mosque's prayer hall
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  A columned arcade within the mosque
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  The courtyard of the mosque

• List of mosques in Saudi Arabia
• Lake Dumat al-Jandal