A historian and geographer, he is regarded as one of the most productive authors of non-religious, scientific literature in the 17th-century Ottoman Empire. He began his studies at the age of five or six, and became an apprentice in the Ottoman financial bureaucracy at the age of fourteen. As the accountant of the commissariat department of the Ottoman army in Anatolia, he accompanied the Ottoman army in the supression of the rebellion of Abaza Mehmed Pasha in 1624, as well as during the Ottoman-Safavid War of 1629-1639, particularly in the campaigns at Baghdad in 1625, and at the siege of Erzurum.
He returned to Constantinople in 1628.
In the following year he was again in Baghdad and Hamadan, and in 1633-1634 at Aleppo, whence he made the pilgrimage to Mecca (hence his title Hajji). The following year he was in Erivan and then returned to Constantinople.
Here he obtained a post in the head office of the commissariat department, which afforded him time for study. An inheritance which he received in 1645 enabled him to live comfortably in the Ottoman capital of Istanbul and dedicate his time to scholarship.
Katip Çelebi died untimely in 1657.
He witnessed the murder of Sultan Osman II in person, and presented the most complete account of this event in his famous book Fezleke in the chapter titled "Osman II at the Central Mosque (Orta Camii)". (Turkish)
There is a university named after him, İzmir Katip Celebi University in İzmir. Turkey and the United Kingdom have an ongoing science and innovation exchange program called the Newton-Katip Çelebi Fund.