The Chaldean Catholic Church (Syriac: ܥܕܬܐ ܟܠܕܝܬܐ ܩܬܘܠܝܩܝܬܐ; ʿītha kaldetha qāthuliqetha), is an Eastern Syriac particular church of the Catholic Church, maintaining full communion with the Bishop of Rome and the rest of the Catholic Church. The Chaldean Catholic Church presently comprises an estimated 1,500,000 Chaldean Christians who are ethnic Assyrians.

The ancient history of the Chaldean Church is the history of the Church of the East. It was originally named The Church of the East. Before the 1553 consecration of Shimun VIII Yohannan Sulaqa, the term Chaldeans had only been officially used previously by the Council of Florence in 1445 as a new name for a group of Greek Nestorians of Cyprus who entered in Full Communion with the Catholic Church.

After the massacres of Tamerlane around 1400 had devastated several bishoprics, the Church of the East, which had previously extended as far as China, was reduced to a handful of Mesopotamian Aramaic Language speaking ethnic Assyrian survivors who lived largely in the triangular area of Northern Mesopotamia between Amid (Diyarbakır), Salmas and Mosul. The See was moved to Alqosh, in the Mosul region and Patriarch Mar Shimun IV Basidi (1437–1493) made the office of patriarch hereditary within his own family.